Enabling rhetorical analysis via the use of communicative discourse trees

ABSTRACT

Systems, devices, and methods of the present invention calculate a rhetorical relationship between one or more sentences. In an example, a computer-implemented method accesses a sentence comprising a plurality of fragments. At least one fragment includes a verb and a words. Each word includes a role of the words within the fragment. Each fragment is an elementary discourse unit. The method generates a discourse tree that represents rhetorical relationships between the sentence fragments. The discourse tree includes nodes including nonterminal and terminal nodes, each nonterminal node representing a rhetorical relationship between two of the sentence fragments, and each terminal node of the nodes of the discourse tree is associated with one of the sentence fragments. The method matches each fragment that has a verb to a verb signature, thereby creating communicative discourse tree.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Application No.62/504,377, filed May 10, 2017, which is incorporated by reference inits entirety.

TECHNICAL FIELD

This disclosure is generally concerned with linguistics. Morespecifically, this disclosure relates to using communicative discoursetrees to perform discourse analysis.

STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSOREDRESEARCH AND DEVELOPMENT

NOT APPLICABLE

BACKGROUND

Linguistics is the scientific study of language. One aspect oflinguistics is the application of computer science to human naturallanguages such as English. Due to the greatly increased speed ofprocessors and capacity of memory, computer applications of linguisticsare on the rise. For example, computer-enabled analysis of languagediscourse facilitates numerous applications such as automated agentsthat can answer questions from users. The use of “chatbots” and agentsto answer questions, facilitate discussion, manage dialogues, andprovide social promotion is increasingly popular. To address this need,a broad range of technologies including compositional semantics has beendeveloped. Such technologies can support automated agents in the case ofsimple, short queries and replies.

But such solutions are unable to leverage rich discourse relatedinformation to answer questions, perform dialog management, providerecommendations or implement “chatbot” systems, because existingsolutions are unable to match an answer with a question due toinsufficient rhetorical analysis. More specifically, statistical basedsolutions are unable to separate the task of determining a topic from asentence and addressing rhetorical agreement between a sentence and ananswer. Statistical-based solutions either do not consider rhetoricalstructure of a question and a response at all, or attempt to addresstopic and rhetorical agreement simultaneously and fail to properlyaddress rhetorical agreement. Without sufficient rhetorical analysis,questions, which can have arbitrary rhetorical structure, cannot bematched with appropriate answers, which may also have arbitraryrhetorical structure.

Hence, new solutions are needed that can accurately represent rhetoricalagreement between a question and an answer.

BRIEF SUMMARY

Generally, systems, devices, and methods of the present invention arerelated to calculating a rhetorical relationship between one or moresentences. In an example, a computer-implemented method accesses asentence including fragments. At least one fragment includes a verb anda word. Each word can play a role within the words within the fragment.Each fragment is an elementary discourse unit. The method generates adiscourse tree that represents rhetorical relationships between thesentence fragments. The discourse tree includes nodes includingnonterminal and terminal nodes, each nonterminal node representing arhetorical relationship between two of the sentence fragments, and eachterminal node of the nodes of the discourse tree is associated with oneof the sentence fragments. The method matches each fragment that has averb to a verb signature, thereby creating communicative discourse tree.

The matching includes accessing multiple verb signatures. Each verbsignature includes the verb of the fragment and a sequence of thematicroles. The method determines, for each verb signature of the verbsignatures, a number of thematic roles of the respective signature thatmatch a role of a word in the fragment. The method selects a particularverb signature from the verb signatures based on the particular verbsignature including a highest number of matches. The method associatesthe particular verb signature with the fragment.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows an exemplary rhetoric classification environment, inaccordance with an aspect.

FIG. 2 depicts an example of a discourse tree in accordance with anaspect.

FIG. 3 depicts a further example of a discourse tree in accordance withan aspect.

FIG. 4 depicts illustrative schemas, in accordance with an aspect.

FIG. 5 depicts a node-link representation of the hierarchical binarytree in accordance with an aspect.

FIG. 6 depicts an exemplary indented text encoding of the representationin FIG. 5 in accordance with an aspect.

FIG. 7 depicts an exemplary DT for an example request about property taxin accordance with an aspect.

FIG. 8 depicts an exemplary response for the question represented inFIG. 7.

FIG. 9 illustrates a discourse tree for an official answer in accordancewith an aspect.

FIG. 10 illustrates a discourse tree for a raw answer in accordance withan aspect.

FIG. 11 illustrates a communicative discourse tree for a claim of afirst agent in accordance with an aspect.

FIG. 12 illustrates a communicative discourse tree for a claim of asecond agent in accordance with an aspect.

FIG. 13 illustrates a communicative discourse tree for a claim of athird agent in accordance with an aspect.

FIG. 14 illustrates parse thickets in accordance with an aspect.

FIG. 15 illustrates an exemplary process for building a communicativediscourse tree in accordance with an aspect.

FIG. 16 illustrates a discourse tree and scenario graph in accordancewith an aspect.

FIG. 17 illustrates forming a request-response pair in accordance withan aspect.

FIG. 18 illustrates a maximal common sub-communicative discourse tree inaccordance with an aspect.

FIG. 19 illustrates a tree in a kernel learning format for acommunicative discourse tree in accordance with an aspect.

FIG. 20 illustrates an exemplary process used to implement a rhetoricagreement classifier in accordance with an aspect.

FIG. 21 illustrates a chat bot commenting on a posting in accordancewith an aspect.

FIG. 22 illustrates a chat bot commenting on a posting in accordancewith an aspect.

FIG. 23 illustrates a discourse tree for algorithm text in accordancewith an aspect.

FIG. 24 illustrates annotated sentences in accordance with an aspect.

FIG. 25 illustrates annotated sentences in accordance with an aspect.

FIG. 26 illustrates discourse acts of a dialogue in accordance with anaspect.

FIG. 27 illustrates discourse acts of a dialogue in accordance with anaspect.

FIG. 28 depicts a simplified diagram of a distributed system forimplementing one of the aspects.

FIG. 29 is a simplified block diagram of components of a systemenvironment by which services provided by the components of an aspectsystem may be offered as cloud services in accordance with an aspect.

FIG. 30 illustrates an exemplary computer system, in which variousaspects of the present invention may be implemented.

DETAILED DESCRIPTION

Aspects disclosed herein provide technical improvements to the area ofcomputer-implemented linguistics. More specifically, aspects describedherein represent rhetorical relationships between one or more sentencesin communicative discourse trees.

“Communicative discourse trees” or “CDTs” include discourse trees thatare supplemented with communicative actions. A communicative action is acooperative action undertaken by individuals based on mutualdeliberation and argumentation.

Using communicative discourse trees, further aspects disclosed hereinimplement improved automated agents, or chatbots, that can answerquestions received from users. Using communicative discourse trees,aspects overcome the limitations of previous systems, which are oftenunable to separate the task of determining a topic from a sentence andaddressing rhetorical agreement between a sentence and an answer.

In an example, a rhetoric classification application executing on acomputing device receives a question from a user. The rhetoricclassification application generates a communicative discourse tree forthe question. A communicative discourse tree is a discourse tree, or atree that a discourse tree that includes communicative actions. Therhetoric classification application accesses a database of potentialanswers to the question. Using a predictive model, the rhetoricagreement application determines a level of complementarity between thequestion and each potential answer. Responsive to determining that thelevel of complementarity is above a threshold, the rhetoric agreementclassifier provides the answer to the user, for example, via a displaydevice.

Technical advantages of some aspects include improved autonomous agentssuch as chatbots and improved search engine performance over traditionalstatistical-based approaches. Traditional statistical keyword-basedapproaches either (i) fail to address the topic of a question, or (ii)fail to address the rhetorical agreement between the question and theanswer. As such, existing autonomous agent solutions are capable of onlyscripted, or limited response to user questions. Such solutions areunable to determine whether an answer is fully responsive to a question.

For example, aspects described herein use, communicative discoursetrees. Communicative discourse trees combine rhetoric information withcommunicative actions. By incorporating labels that identifycommunicative actions, learning of communicative discourse trees canoccur over a richer features set than simply rhetoric relations andsyntax of elementary discourse units (EDUs). With such a feature set,additional techniques such as classification can be used to determine alevel of rhetoric agreement between questions and answers orrequest-response pairs, thereby enabling improved automated agents. Inso doing, computing systems enable autonomous agents that are capable ofintelligently answering questions and other messages.

Certain Definitions

As used herein, “rhetorical structure theory” is an area of research andstudy that provided a theoretical basis upon which the coherence of adiscourse could be analyzed.

As used herein, “discourse tree” or “DT” refers to a structure thatrepresents the rhetorical relations for a sentence of part of asentence.

As used herein, a “rhetorical relation,” “rhetorical relationship,” or“coherence relation” or “discourse relation” refers to how two segmentsof discourse are logically connected to one another. Examples ofrhetorical relations include elaboration, contrast, and attribution.

As used herein, a “sentence fragment,” or “fragment” is a part of asentence that can be divided from the rest of the sentence. A fragmentis an elementary discourse unit. For example, for the sentence “Dutchaccident investigators say that evidence points to pro-Russian rebels asbeing responsible for shooting down the plane,” two fragments are “Dutchaccident investigators say that evidence points to pro-Russian rebels”and “as being responsible for shooting down the plane.” A fragment can,but need not, include a verb.

As used herein, “signature” or “frame” refers to a property of a verb ina fragment. Each signature can include one or more thematic roles. Forexample, for the fragment “Dutch accident investigators say thatevidence points to pro-Russian rebels,” the verb is “say” and thesignature of this particular use of the verb “say” could be “agent verbtopic” where “investigators” is the agent and “evidence” is the topic.

As used herein, “thematic role” refers to components of a signature usedto describe a role of one or more words. Continuing the previousexample, “agent” and “topic” are thematic roles.

As used herein, “nuclearity” refers to which text segment, fragment, orspan, is more central to a writer's purpose. The nucleus is the morecentral span, and the satellite is the less central one.

As used herein, “coherency” refers to the linking together of tworhetorical relations.

As used herein, “communicative verb” is a verb that indicatescommunication. For example, the verb “deny” is a communicative verb.

As used herein, “communicative action” describes an action performed byone or more agents and the subjects of the agents.

FIG. 1 shows an exemplary rhetoric classification environment, inaccordance with an aspect. FIG. 1 depicts rhetoric classificationcomputing device 101, input question 130, output question 150, datanetwork 104, server 160, and mobile device 170. Rhetoric classificationcomputing device 101 includes one or more of rhetoric classificationapplication 102, answer database 105, rhetoric agreement classifier 120,and training data 125. Rhetoric classification application 102 includesone or more of question communicative discourse tree 110, answercommunicative discourse tree 110.

Mobile device 170 can be any mobile device such as a mobile phone, smartphone, tablet, laptop, smart watch, and the like. Mobile device 170communicates via data network 104 to server 160 or rhetoricclassification computing device 101. In this manner, mobile device 170can provide question 171, e.g., from a user, to server 160 or rhetoricclassification computing device 101. In an example rhetoricclassification computing device 101 determines a suitable answer 172 andprovides answer 172, over data network 104, to mobile device 170.

Data network 104 can be any public or private network, wired or wirelessnetwork, Wide Area Network, Local Area Network, or the Internet.

In an example, rhetoric classification application 102 answers aquestion received via chat. More specifically, rhetoric classificationapplication 102 receives input question 130, which can be a singlequestion or a stream of questions such as a chat. Rhetoricclassification application 102 creates question communicative discoursetree 110 and selects one or more candidate answers. The answers can beobtained from an existing database such as the answer database 105 orfrom server 160, communicating over data network 104. Server 160 can bea public or private internet server, such as a public database of userquestions and answers.

From the candidate answer, rhetoric classification application 102determines the most suitable answer. As further explained herein,different methods can be used. In an aspect, rhetoric classificationapplication 102 can create a candidate answer communicative discoursetree for each candidate answer and compare question communicativediscourse tree 110 with each candidate discourse tree. Rhetoricclassification application 102 identifies a best match between questioncommunicative discourse tree and the candidate answer communicativediscourse trees. The rhetoric classification application 102 thenaccesses or queries a database for the text from the best communicativediscourse tree. Rhetoric classification application 102 then sends textassociated with the second communicative discourse tree to a mobiledevice.

In another aspect, rhetoric classification application 102 creates ananswer communicative discourse tree 111 for each candidate answer.Rhetoric classification application 102 then, for each candidate answer,creates a question-answer pair that includes the question 130 and thecandidate answer.

Rhetoric classification application 102 provides the question-answerpairs to a predictive model such as rhetoric agreement classifier 120.Using a trained rhetoric agreement classifier 120, rhetoricclassification application 102 determines whether the question-answerpair is above a threshold level of matching, e.g., indicating whetherthe answer addresses the question. If not, the rhetoric classificationapplication 102 continues to analyze additional pairs that include thequestion and a different answer until a suitable answer is found. Byusing communicative discourse trees, the rhetorical agreement andcommunicative actions between the question and answer can be accuratelymodeled.

Rhetoric classification application 102 provides the answer as outputanswer 150. For example, as depicted in FIG. 1, an agent, implemented byrhetoric classification application 102, has provided the text “here ismy own personal list of songs” in response to a chat history thatinvolved two users discussing singing out loud.

Rhetoric Structure Theory and Discourse Trees

Linguistics is the scientific study of language. For example,linguistics can include the structure of a sentence (syntax), e.g.,subject-verb-object, the meaning of a sentence (semantics), e.g. dogbites man vs. man bites dog, and what speakers do in conversation, i.e.,discourse analysis or the analysis of language beyond the sentence.

The theoretical underpinnings of discourse, Rhetoric Structure Theory(RST), can be attributed to Mann, William and Thompson, Sandra,“Rhetorical structure theory: A Theory of Text organization,”Text-Interdisciplinary Journal for the Study of Discourse, 8(3):243-281,1988. Similar to how the syntax and semantics of programming languagetheory helped enable modern software compilers, RST helped enabled theanalysis of discourse. More specifically RST posits structural blocks onat least two levels, a first level such as nuclearity and rhetoricalrelations, and a second level of structures or schemas. Discourseparsers or other computer software can parse text into a discourse tree.

Rhetoric Structure Theory models logical organization of text, astructure employed by a writer, relying on relations between parts oftext. RST simulates text coherence by forming a hierarchical, connectedstructure of texts via discourse trees. Rhetoric relations are splitinto the classes of coordinate and subordinate; these relations holdacross two or more text spans and therefore implement coherence. Thesetext spans are called elementary discourse units (EDUs). Clauses in asentence and sentences in a text are logically connected by the author.The meaning of a given sentence is related to that of the previous andthe following sentences. This logical relation between clauses is calledthe coherence structure of the text. RST is one of the most populartheories of discourse, being based on a tree-like discourse structure,discourse trees (DTs). The leaves of a DT correspond to EDUs, thecontiguous atomic text spans. Adjacent EDUs are connected by coherencerelations (e.g., Attribution, Sequence), forming higher-level discourseunits. These units are then also subject to this relation linking. EDUslinked by a relation are then differentiated based on their relativeimportance: nuclei are the core parts of the relation, while satellitesare peripheral ones. As discussed, in order to determine accuraterequest-response pairs, both topic and rhetorical agreement areanalyzed. When a speaker answers a question, such as a phrase or asentence, the speaker's answer should address the topic of thisquestion. In the case of an implicit formulation of a question, via aseed text of a message, an appropriate answer is expected not onlymaintain a topic, but also match the generalized epistemic state of thisseed.

Rhetoric Relations

As discussed, aspects described herein use communicative discoursetrees. Rhetorical relations can be described in different ways. Forexample, Mann and Thompson describe twenty-three possible relations. C.Mann, William & Thompson, Sandra. (1987) (“Mann and Thompson”).Rhetorical Structure Theory: A Theory of Text Organization. Othernumbers of relations are possible.

Relation Name Nucleus Satellite Antithesis ideas favored by the ideasdisfavored author by the author Background text whose text forfacilitating understanding is being understanding facilitatedCircumstance text expressing the an interpretive context events or ideasof situation or time occurring in the interpretive context Concessionsituation affirmed by situation which is author apparently inconsistentbut also affirmed by author Condition action or situation conditioningsituation whose occurrence results from the occurrence of theconditioning situation Elaboration basic information additionalinformation Enablement an action information intended to aid the readerin performing an action Evaluation a situation an evaluative commentabout the situation Evidence a claim information intended to increasethe reader's belief in the claim Interpretation a situation aninterpretation of the situation Justify text information supporting thewriter's right to express the text Motivation an action informationintended to increase the reader's desire to perform the action Non- asituation another situation which volitional causes that one, but not byCause anyone's deliberate action Non- a situation another situationwhich is volitional caused by that one, but not Result by anyone'sdeliberate action Otherwise action or situation conditioning situation(anti whose occurrence conditional) results from the lack of occurrenceof the conditioning situation Purpose an intended situation the intentbehind the situation Restatement a situation a reexpression of thesituation Solutionhood a situation or method a question, request,problem, supporting full or partial or other expressed need satisfactionof the need Summary text a short summary of that text Volitional asituation another situation which causes Cause that one, by someone'sdeliberate action Volitional a situation another situation which isResult caused by that one, by someone's deliberate action

Some empirical studies postulate that the majority of text is structuredusing nucleus-satellite relations. See Mann and Thompson. But otherrelations do not carry a definite selection of a nucleus. Examples ofsuch relations are shown below.

Relation Name Span Other Span Contrast One alternate The other alternateJoint (unconstrained) (unconstrained) List An item A next item SequenceAn item A next item

FIG. 2 depicts an example of a discourse tree, in accordance with anaspect. FIG. 2 includes discourse tree 200. Discourse tree includes textspan 201, text span 202, text span 203, relation 210 and relation 228.The numbers in FIG. 2 correspond to the three text spans. FIG. 3corresponds to the following example text with three text spans numbered1, 2, 3:

1. Honolulu, Hi. will be site of the 2017 Conference on Hawaiian History

2. It is expected that 200 historians from the U.S. and Asia will attend

3. The conference will be concerned with how the Polynesians sailed toHawaii

For example, relation 210, or elaboration, describes the relationshipbetween text span 201 and text span 202. Relation 228 depicts therelationship, elaboration, between text span 203 and 204. As depicted,text spans 202 and 203 elaborate further on text span 201. In the aboveexample, given a goal of notifying readers of a conference, text span 1is the nucleus. Text spans 2 and 3 provide more detail about theconference. In FIG. 2, a horizontal number, e.g., 1-3, 1, 2, 3 covers aspan of text (possibly made up of further spans); a vertical linesignals the nucleus or nuclei; and a curve represents a rhetoricrelation (elaboration) and the direction of the arrow points from thesatellite to the nucleus. If the text span only functions as a satelliteand not as a nuclei, then deleting the satellite would still leave acoherent text. If from FIG. 2 one deletes the nucleus, then text spans 2and 3 are difficult to understand.

FIG. 3 depicts a further example of a discourse tree in accordance withan aspect. FIG. 3 includes components 301 and 302, text spans 305-307,relation 310 and relation 328. Relation 310 depicts the relationship310, enablement, between components 306 and 305, and 307, and 305. FIG.3 refers to the following text spans:

1. The new Tech Report abstracts are now in the journal area of thelibrary near the abridged dictionary.

2. Please sign your name by any means that you would be interested inseeing.

3. Last day for sign-ups is 31 May.

As can be seen, relation 328 depicts the relationship between entity 307and 306, which is enablement. FIG. 3 illustrates that while nuclei canbe nested, there exists only one most nuclear text span.

Constructing a Discourse Tree

Discourse trees can be generated using different methods. A simpleexample of a method to construct a DT bottom up is:

(1) Divide the discourse text into units by:

-   -   (a) Unit size may vary, depending on the goals of the analysis    -   (b) Typically, units are clauses

(2) Examine each unit, and its neighbors. Is there a relation holdingbetween them?

(3) If yes, then mark that relation.

(4) If not, the unit might be at the boundary of a higher-levelrelation. Look at relations holding between larger units (spans).

(5) Continue until all the units in the text are accounted for.

Mann and Thompson also describe the second level of building blockstructures called schemas applications. In RST, rhetoric relations arenot mapped directly onto texts; they are fitted onto structures calledschema applications, and these in turn are fitted to text. Schemaapplications are derived from simpler structures called schemas (asshown by FIG. 4). Each schema indicates how a particular unit of text isdecomposed into other smaller text units. A rhetorical structure tree orDT is a hierarchical system of schema applications. A schema applicationlinks a number of consecutive text spans, and creates a complex textspan, which can in turn be linked by a higher-level schema application.RST asserts that the structure of every coherent discourse can bedescribed by a single rhetorical structure tree, whose top schemacreates a span encompassing the whole discourse.

FIG. 4 depicts illustrative schemas, in accordance with an aspect. FIG.4 shows a joint schema is a list of items consisting of nuclei with nosatellites. FIG. 4 depicts schemas 401-406. Schema 401 depicts acircumstance relation between text spans 410 and 428. Scheme 402 depictsa sequence relation between text spans 420 and 421 and a sequencerelation between text spans 421 and 422. Schema 403 depicts a contrastrelation between text spans 430 and 431. Schema 404 depicts a jointrelationship between text spans 440 and 441. Schema 405 depicts amotivation relationship between 450 and 451, and an enablementrelationship between 452 and 451. Schema 406 depicts joint relationshipbetween text spans 460 and 462. An example of a joint scheme is shown inFIG. 4 for the three text spans below:

1. Skies will be partly sunny in the New York metropolitan area today.

2. It will be more humid, with temperatures in the middle 80's.

3. Tonight will be mostly cloudy, with the low temperature between 65and 70.

While FIGS. 2-4 depict some graphical representations of a discoursetree, other representations are possible.

FIG. 5 depicts a node-link representation of the hierarchical binarytree in accordance with an aspect. As can be seen from FIG. 5, theleaves of a DT correspond to contiguous non-overlapping text spanscalled Elementary Discourse Units (EDUs). Adjacent EDUs are connected byrelations (e.g., elaboration, attribution . . . ) and form largerdiscourse units, which are also connected by relations. “Discourseanalysis in RST involves two sub-tasks: discourse segmentation is thetask of identifying the EDUs, and discourse parsing is the task oflinking the discourse units into a labeled tree.” See Joty, Shafiq R andGiuseppe Carenini, Raymond T Ng, and Yashar Mehdad. 2013. Combiningintra- and multi-sentential rhetorical parsing for document-leveldiscourse analysis. In ACL (1), pages 486-496.

FIG. 5 depicts text spans that are leaves, or terminal nodes, on thetree, each numbered in the order they appear in the full text, shown inFIG. 6. FIG. 5 includes tree 500. Tree 500 includes, for example, nodes501-507. The nodes indicate relationships. Nodes are non-terminal, suchas node 501, or terminal, such as nodes 502-507. As can be seen, nodes503 and 504 are related by a joint relationship. Nodes 502, 505, 506,and 508 are nuclei. The dotted lines indicate that the branch or textspan is a satellite. The relations are nodes in gray boxes.

FIG. 6 depicts an exemplary indented text encoding of the representationin FIG. 5 in accordance with an aspect. FIG. 6 includes text 600 andtext sequences 602-604. Text 600 is presented in a manner more amenableto computer programming. Text sequence 602 corresponds to node 502,sequence 603 corresponds to node 503, and sequence 604 corresponds tonode 504. In FIG. 6, “N” indicates a nucleus and “S” indicates asatellite.

Examples of Discourse Parsers

Automatic discourse segmentation can be performed with differentmethods. For example, given a sentence, a segmentation model identifiesthe boundaries of the composite elementary discourse units by predictingwhether a boundary should be inserted before each particular token inthe sentence. For example, one framework considers each token in thesentence sequentially and independently. In this framework, thesegmentation model scans the sentence token by token, and uses a binaryclassifier, such as a support vector machine or logistic regression, topredict whether it is appropriate to insert a boundary before the tokenbeing examined. In another example, the task is a sequential labelingproblem. Once text is segmented into elementary discourse units,sentence-level discourse parsing can be performed to construct thediscourse tree. Machine learning techniques can be used.

In one aspect of the present invention, two Rhetorical Structure Theory(RST) discourse parsers are used: CoreNLPProcessor which relies onconstituent syntax, and FastNLPProcessor which uses dependency syntax.See Surdeanu, Mihai & Hicks, Thomas & Antonio Valenzuela-Escarcega,Marco. Two Practical Rhetorical Structure Theory Parsers. (2015).

In addition, the above two discourse parsers, i.e., CoreNLPProcessor andFastNLPProcessor use Natural Language Processing (NLP) for syntacticparsing. For example, the Stanford CoreNLP gives the base forms ofwords, their parts of speech, whether they are names of companies,people, etc., normalize dates, times, and numeric quantities, mark upthe structure of sentences in terms of phrases and syntacticdependencies, indicate which noun phrases refer to the same entities.Practically, RST is a still theory that may work in many cases ofdiscourse, but in some cases, it may not work. There are many variablesincluding, but not limited to, what EDU's are in a coherent text, i.e.,what discourse segmenters are used, what relations inventory is used andwhat relations are selected for the EDUs, the corpus of documents usedfor training and testing, and even what parsers are used. So forexample, in Surdeanu, et al., “Two Practical Rhetorical Structure TheoryParsers,” paper cited above, tests must be run on a particular corpususing specialized metrics to determine which parser gives betterperformance. Thus unlike computer language parsers which givepredictable results, discourse parsers (and segmenters) can giveunpredictable results depending on the training and/or test text corpus.Thus, discourse trees are a mixture of the predicable arts (e.g.,compilers) and the unpredictable arts (e.g., like chemistry wereexperimentation is needed to determine what combinations will give youthe desired results).

In order to objectively determine how good a Discourse analysis is, aseries of metrics are being used, e.g., Precision/Recall/F1 metrics fromDaniel Marcu, “The Theory and Practice of Discourse Parsing andSummarization,” MIT Press, (2000). Precision, or positive predictivevalue is the fraction of relevant instances among the retrievedinstances, while recall (also known as sensitivity) is the fraction ofrelevant instances that have been retrieved over the total amount ofrelevant instances. Both precision and recall are therefore based on anunderstanding and measure of relevance. Suppose a computer program forrecognizing dogs in photographs identifies eight dogs in a picturecontaining 12 dogs and some cats. Of the eight dogs identified, fiveactually are dogs (true positives), while the rest are cats (falsepositives). The program's precision is 5/8 while its recall is 5/12.When a search engine returns 30 pages only 20 of which were relevantwhile failing to return 40 additional relevant pages, its precision is20/30=2/3 while its recall is 20/60=1/3. Therefore, in this case,precision is ‘how useful the search results are’, and recall is ‘howcomplete the results are.’” The F1 score (also F-score or F-measure) isa measure of a test's accuracy. It considers both the precision and therecall of the test to compute the score:F1=2×((precision×recall)/(precision+recall)) and is the harmonic mean ofprecision and recall. The F1 score reaches its best value at 1 (perfectprecision and recall) and worst at 0.

Autonomous Agents or Chatbots

A conversation between Human A and Human B is a form of discourse. Forexample, applications exist such as FaceBook® Messenger, WhatsApp®,Slack,® SMS, etc., a conversation between A and B may typically be viamessages in addition to more traditional email and voice conversations.A chatbot (which may also be called intelligent bots or virtualassistant, etc.) is an “intelligent” machine that, for example, replaceshuman B and to various degrees mimics the conversation between twohumans. An example ultimate goal is that human A cannot tell whether Bis a human or a machine (the Turning test, developed by Alan Turing in1950). Discourse analysis, artificial intelligence, including machinelearning, and natural language processing, have made great stridestoward the long-term goal of passing the Turing test. Of course, withcomputers being more and more capable of searching and processing vastrepositories of data and performing complex analysis on the data toinclude predictive analysis, the long-term goal is the chatbot beinghuman-like and a computer combined.

For example, users can interact with the Intelligent Bots Platformthrough a conversational interaction. This interaction, also called theconversational user interface (UI), is a dialog between the end user andthe chatbot, just as between two human beings. It could be as simple asthe end user saying “Hello” to the chatbot and the chatbot respondingwith a “Hi” and asking the user how it can help, or it could be atransactional interaction in a banking chatbot, such as transferringmoney from one account to the other, or an informational interaction ina HR chatbot, such as checking for vacation balance, or asking an FAQ ina retail chatbot, such as how to handle returns. Natural languageprocessing (NLP) and machine learning (ML) algorithms combined withother approaches can be used to classify end user intent. An intent at ahigh level is what the end user would like to accomplish (e.g., getaccount balance, make a purchase). An intent is essentially, a mappingof customer input to a unit of work that the backend should perform.Therefore, based on the phrases uttered by the user in the chatbot,these are mapped that to a specific and discrete use case or unit ofwork, for e.g. check balance, transfer money and track spending are all“use cases” that the chatbot should support and be able to work outwhich unit of work should be triggered from the free text entry that theend user types in a natural language.

The underlying rational for having an AI chatbot respond like a human isthat the human brain can formulate and understand the request and thengive a good response to the human request much better than a machine.Thus, there should be significant improvement in the request/response ofa chatbot, if human B is mimicked. So an initial part of the problem ishow does the human brain formulate and understand the request? To mimic,a model is used. RST and DT allow a formal and repeatable way of doingthis.

At a high level, there are typically two types of requests: (1) Arequest to perform some action; and (2) a request for information, e.g.,a question. The first type has a response in which a unit of work iscreated. The second type has a response that is, e.g., a good answer, tothe question. The answer could take the form of, for example, in someaspects, the AI constructing an answer from its extensive knowledgebase(s) or from matching the best existing answer from searching theinternet or intranet or other publically/privately available datasources.

Communicative Discourse Trees and the Rhetoric Classifier

Aspects of the present disclosure build communicative discourse treesand use communicative discourse trees to analyze whether the rhetoricalstructure of a request or question agrees with an answer. Morespecifically, aspects described herein create representations of arequest-response pair, learns the representations, and relates the pairsinto classes of valid or invalid pairs. In this manner, an autonomousagent can receive a question from a user, process the question, forexample, by searching for multiple answers, determine the best answerfrom the answers, and provide the answer to the user.

More specifically, to represent linguistic features of text, aspectsdescribed herein use rhetoric relations and speech acts (orcommunicative actions). Rhetoric relations are relationships between theparts of the sentences, typically obtained from a discourse tree. Speechacts are obtained as verbs from a verb resource such as VerbNet. Byusing both rhetoric relations and communicative actions, aspectsdescribed herein can correctly recognize valid request-response pairs.To do so, aspects correlate the syntactic structure of a question withthat of an answer. By using the structure, a better answer can bedetermined.

For example, when an autonomous agent receives an indication from aperson that the person desires to sell an item with certain features,the autonomous agent should provide a search result that not onlycontains the features but also indicates an intent to buy. In thismanner, the autonomous agent has determined the user's intent.Similarly, when an autonomous agent receives a request from a person toshare knowledge about a particular item, the search result shouldcontain an intent to receive a recommendation. When a person asks anautonomous agent for an opinion about a subject, the autonomous agentshares an opinion about the subject, rather than soliciting anotheropinion.

Analyzing Request and Response Pairs

FIG. 7 depicts an exemplary DT for an example request about property taxin accordance with an aspect. The node labels are the relations and thearrowed line points to the satellite. The nucleus is a solid line. FIG.7 depicts the following text.

Request: “My husbands’ grandmother gave him his grandfather's truck. Shesigned the title over but due to my husband having unpaid fines on hislicense, he was not able to get the truck put in his name. I wanted toput in my name and paid the property tax and got insurance for thetruck. By the time it came to sending off the title and getting the tag,I didn't have the money to do so. Now, due to circumstances, I am notgoing to be able to afford the truck. I went to the insurance place andwas refused a refund. I am just wondering that since I am not going tohave a tag on this truck, is it possible to get the property taxrefunded?”

Response: “The property tax is assessed on property that you own. Justbecause you chose to not register it does not mean that you don't ownit, so the tax is not refundable. Even if you have not titled thevehicle yet, you still own it within the boundaries of the tax district,so the tax is payable. Note that all states give you a limited amount oftime to transfer title and pay the use tax. If you apply late, therewill be penalties on top of the normal taxes and fees. You don't need toregister it at the same time, but you absolutely need to title it withinthe period of time stipulated in state law.”

As can be seen in FIG. 7, analyzing the above text results in thefollowing. “My husbands' grandmother gave him his grandfather's truck”is elaborated by “She signed the title over but due to my husband”elaborated by “having unpaid fines on his license, he was not able toget the truck put in his name.” which is elaborated by “I wanted to putin my name,” “and paid the property tax”, and “and got insurance for thetruck.”

“My husbands' grandmother gave him his grandfather's truck. She signedthe title over but due to my husband having unpaid fines on his license,he was not able to get the truck put in his name. I wanted to put in myname and paid the property tax and got insurance for the truck.” iselaborated by;

“I didn't have the money” elaborated by “to do so” contrasted with

“By the time” elaborated by “it came to sending off the title”

“and getting the tag”

“My husbands' grandmother gave him his grandfather's truck. She signedthe title over but due to my husband having unpaid fines on his license,he was not able to get the truck put in his name. I wanted to put in myname and paid the property tax and got insurance for the truck. By thetime it came to sending off the title and getting the tag, I didn't havethe money to do so” is contrasted with

“Now, due to circumstances,” elaborated with “I am not going to be ableto afford the truck.” which is elaborated with

“I went to the insurance place”

“and was refused a refund”

“My husbands' grandmother gave him his grandfather's truck. She signedthe title over but due to my husband having unpaid fines on his license,he was not able to get the truck put in his name. I wanted to put in myname and paid the property tax and got insurance for the truck. By thetime it came to sending off the title and getting the tag, I didn't havethe money to do so. Now, due to circumstances, I am not going to be ableto afford the truck. I went to the insurance place and was refused arefund.” is elaborated with

“I am just wondering that since I am not going to have a tag on thistruck, is it possible to get the property tax refunded?”

“I am just wondering” has attribution to

“that” is the same unit as “is it possible to get the property taxrefunded?” which has condition “since I am not going to have a tag onthis truck”

As can be seen, the main subject of the topic is “Property tax on acar”. The question includes the contradiction: on one hand, allproperties are taxable, and on the other hand, the ownership is somewhatincomplete. A good response has to address both topic of the questionand clarify the inconsistency. To do that, the responder is making evenstronger claim concerning the necessity to pay tax on whatever is ownedirrespectively of the registration status. This example is a member ofpositive training set from our Yahoo! Answers evaluation domain. Themain subject of the topic is “Property tax on a car”. The questionincludes the contradiction: on one hand, all properties are taxable, andon the other hand, the ownership is somewhat incomplete. A goodanswer/response has to address both topic of the question and clarifythe inconsistency. The reader can observe that since the questionincludes rhetoric relation of contrast, the answer has to match it witha similar relation to be convincing. Otherwise, this answer would lookincomplete even to those who are not domain experts.

FIG. 8 depicts an exemplary response for the question represented inFIG. 7, according to certain aspects of the present invention. Thecentral nucleus is “the property tax is assessed on property” elaboratedby “that you own”. “The property tax is assessed on property that youown” is also a nucleus elaborated by “Just because you chose to notregister it does not mean that you don't own it, so the tax is notrefundable. Even if you have not titled the vehicle yet, you still ownit within the boundaries of the tax district, so the tax is payable.Note that all states give you a limited amount of time to transfer titleand pay the use tax.”

The nucleus “The property tax is assessed on property that you own. Justbecause you chose to not register it does not mean that you don't ownit, so the tax is not refundable. Even if you have not titled thevehicle yet, you still own it within the boundaries of the tax district,so the tax is payable. Note that all states give you a limited amount oftime to transfer title and pay the use tax.” is elaborated by “therewill be penalties on top of the normal taxes and fees” with condition“If you apply late,” which in turn is elaborated by the contrast of “butyou absolutely need to title it within the period of time stipulated instate law.” and “You don't need to register it at the same time.”.

Comparing the DT of FIG. 7 and DT of FIG. 8, enables a determination ofhow well matched the response (FIG. 8) is to the request (FIG. 7). Insome aspects of the present invention, the above framework is used, atleast in part, to determine the DTs for the request/response and therhetoric agreement between the DTs.

In another example, the question “What does The Investigative Committeeof the Russian Federation do” has at least two answers, for example, anofficial answer or an actual answer.

FIG. 9 illustrates a discourse tree for an official answer in accordancewith an aspect. As depicted in FIG. 9, an official answer, or missionstatement states that “The Investigative Committee of the RussianFederation is the main federal investigating authority which operates asRussia's Anti-corruption agency and has statutory responsibility forinspecting the police forces, combating police corruption and policemisconduct, is responsible for conducting investigations into localauthorities and federal governmental bodies.”

FIG. 10 illustrates a discourse tree for a raw answer in accordance withan aspect. As depicted in FIG. 10, another, perhaps more honest, answerstates that “Investigative Committee of the Russian Federation issupposed to fight corruption. However, top-rank officers of theInvestigative Committee of the Russian Federation are charged withcreation of a criminal community. Not only that, but their involvementin large bribes, money laundering, obstruction of justice, abuse ofpower, extortion, and racketeering has been reported. Due to theactivities of these officers, dozens of high-profile cases including theones against criminal lords had been ultimately ruined.”

The choice of answers depends on context. Rhetoric structure allowsdifferentiating between “official”, “politically correct”,template-based answers and “actual”, “raw”, “reports from the field”, or“controversial” answers. (See FIG. 9 and FIG. 10). Sometimes, thequestion itself can give a hint about which category of answers isexpected. If a question is formulated as a factoid or definitional one,without a second meaning, then the first category of answers issuitable. Otherwise, if a question has the meaning “tell me what itreally is”, then the second category is appropriate. In general, afterextracting a rhetoric structure from a question, selecting a suitableanswer that would have a similar, matching, or complementary rhetoricstructure is easier.

The official answer is based on elaboration and joints, which areneutral in terms of controversy a text might contain (See FIG. 9). Atthe same time, the row answer includes the contrast relation. Thisrelation is extracted between the phrase for what an agent is expectedto do and what this agent was discovered to have done.

Classification of Request-Response Pairs

Rhetoric classification application 102 can determine whether a givenanswer or response, such as an answer obtained from answer database 105or a public database, is responsive to a given question, or request.More specifically, rhetoric classification application 102 analyzeswhether a request and response pair is correct or incorrect bydetermining one or both of (i) relevance or (ii) rhetoric agreementbetween the request and the response. Rhetoric agreement can be analyzedwithout taking into account relevance, which can be treatedorthogonally.

Rhetoric classification application 102 can determine similarity betweenquestion-answer pairs using different methods. For example, rhetoricclassification application 102 can determine level of similarity betweenan individual question and an individual answer. Alternatively, rhetoricclassification application 102 can determine a measure of similaritybetween a first pair including a question and an answer, and a secondpair including a question and answer.

For example, rhetoric classification application 102 uses rhetoricagreement classifier 120 trained to predict matching or non-matchinganswers. Rhetoric classification application 102 can process two pairsat a time, for example <q1,a1> and <q2,a2>. Rhetoric classificationapplication 102 compares q1 with q2 and a1 with a1, producing a combinedsimilarity score. Such a comparison allows a determination of whether anunknown question/answer pair contains a correct answer or not byassessing a distance from another question/answer pair with a knownlabel. In particular, an unlabeled pair <q2, a2> can be processed sothat rather than “guessing” correctness based on words or structuresshared by q2 and a2, both q2 and a2 can be compared with theircorresponding components q1 and a2 of the labeled pair <q2, a2> on thegrounds of such words or structures. Because this approach targets adomain-independent classification of an answer, only the structuralcohesiveness between a question and answer can be leveraged, not‘meanings’ of answers.

In an aspect, rhetoric classification application 102 uses training data125 to train rhetoric agreement classifier 120. In this manner, rhetoricagreement classifier 120 is trained to determine a similarity betweenpairs of questions and answers. This is a classification problem.Training data 125 can include a positive training set and a negativetraining set. Training data 125 includes matching request-response pairsin a positive dataset and arbitrary or lower relevance orappropriateness request-response pairs in a negative dataset. For thepositive dataset, various domains with distinct acceptance criteria areselected that indicate whether an answer or response is suitable for thequestion.

Each training data set includes a set of training pairs. Each trainingset includes a question communicative discourse tree that represents aquestion and an answer communicative discourse tree that represents ananswer and an expected level of complementarity between the question andanswer. By using an iterative process, rhetoric classificationapplication 102 provides a training pair to rhetoric agreementclassifier 120 and receives, from the model, a level of complementarity.Rhetoric classification application 102 calculates a loss function bydetermining a difference between the determined level of complementarityand an expected level of complementarity for the particular trainingpair. Based on the loss function, rhetoric classification application102 adjusts internal parameters of the classification model to minimizethe loss function.

Acceptance criteria can vary by application. For example, acceptancecriteria may be low for community question answering, automated questionanswering, automated and manual customer support systems, social networkcommunications and writing by individuals such as consumers about theirexperience with products, such as reviews and complaints. RR acceptancecriteria may be high in scientific texts, professional journalism,health and legal documents in the form of FAQ, professional socialnetworks such as “stackoverflow.”

Communicative Discourse Trees (CDTs)

Rhetoric classification application 102 can create, analyze, and comparecommunicative discourse trees. Communicative discourse trees aredesigned to combine rhetoric information with speech act structures.CDTs include with arcs labeled with expressions for communicativeactions. By combining communicative actions, CDTs enable the modeling ofRST relations and communicative actions. A CDT is a reduction of a parsethicket. See Galitsky, B, Ilvovsky, D. and Kuznetsov S O. Rhetoric Mapof an Answer to Compound Queries Knowledge Trail Inc. ACL 2015, 681-686.(“Galitsky 2015”). A parse thicket is a combination of parse trees forsentences with discourse-level relationships between words and parts ofthe sentence in one graph. By incorporating labels that identify speechactions, learning of communicative discourse trees can occur over aricher features set than just rhetoric relations and syntax ofelementary discourse units (EDUs).

In an example, a dispute between three parties concerning the causes ofa downing of a commercial airliner, Malaysia Airlines Flight 17 isanalyzed. An RST representation of the arguments being communicated isbuilt. In the example, three conflicting agents, Dutch investigators,The Investigative Committee of the Russian Federation, and theself-proclaimed Donetsk People's Republic exchange their opinions on thematter. The example illustrates a controversial conflict where eachparty does all it can to blame its opponent. To sound more convincing,each party does not just produce its claim but formulates a response ina way to rebuff the claims of an opponent. To achieve this goal, eachparty attempts to match the style and discourse of the opponents'claims.

FIG. 11 illustrates a communicative discourse tree for a claim of afirst agent in accordance with an aspect. FIG. 11 depicts communicativediscourse tree 100, which represents the following text: “Dutch accidentinvestigators say that evidence points to pro-Russian rebels as beingresponsible for shooting down plane. The report indicates where themissile was fired from and identifies who was in control of theterritory and pins the downing of MH17 on the pro-Russian rebels.”

As can be seen from FIG. 11, non-terminal nodes of CDTs are rhetoricrelations, and terminal nodes are elementary discourse units (phrases,sentence fragments) which are the subjects of these relations. Certainarcs of CDTs are labeled with the expressions for communicative actions,including the actor agent and the subject of these actions (what isbeing communicated). For example, the nucleus node for elaborationrelation (on the left) are labeled with say (Dutch, evidence), and thesatellite with responsible (rebels, shooting down). These labels are notintended to express that the subjects of EDUs are evidence and shootingdown but instead for matching this CDT with others for the purpose offinding similarity between them. In this case just linking thesecommunicative actions by a rhetoric relation and not providinginformation of communicative discourse would be too limited way torepresent a structure of what and how is being communicated. Arequirement for an RR pair to have the same or coordinated rhetoricrelation is too weak, so an agreement of CDT labels for arcs on top ofmatching nodes is required.

The straight edges of this graph are syntactic relations, and curvy arcsare discourse relations, such as anaphora, same entity, sub-entity,rhetoric relation and communicative actions. This graph includes muchricher information than just a combination of parse trees for individualsentences. In addition to CDTs, parse thickets can be generalized at thelevel of words, relations, phrases and sentences. The speech actions arelogic predicates expressing the agents involved in the respective speechacts and their subjects. The arguments of logical predicates are formedin accordance to respective semantic roles, as proposed by a frameworksuch as VerbNet. See Karin Kipper, Anna Korhonen, Neville Ryant, MarthaPalmer, A Large-scale Classification of English Verbs, LanguageResources and Evaluation Journal, 42(1), pp. 21-40, Springer Netherland,2008. and/or Karin Kipper Schuler, Anna Korhonen, Susan W. Brown,VerbNet overview, extensions, mappings and apps, Tutorial, NAACL-HLT2009, Boulder, Colo.

FIG. 12 illustrates a communicative discourse tree for a claim of asecond agent in accordance with an aspect. FIG. 12 depicts communicativediscourse tree 1200, which represents the following text: “TheInvestigative Committee of the Russian Federation believes that theplane was hit by a missile, which was not produced in Russia. Thecommittee cites an investigation that established the type of themissile.”

FIG. 13 illustrates a communicative discourse tree for a claim of athird agent in accordance with an aspect. FIG. 13 depicts communicativediscourse tree 1300, which represents the following text: “Rebels, theself-proclaimed Donetsk People's Republic, deny that they controlled theterritory from which the missile was allegedly fired. It became possibleonly after three months after the tragedy to say if rebels controlledone or another town.”

As can be seen from communicative discourse trees 1100-1300, a responseis not arbitrary. A response talks about the same entities as theoriginal text. For example, communicative discourse trees 1200 and 1300are related to communicative discourse tree 1100. A response backs up adisagreement with estimates and sentiments about these entities, andabout actions of these entities.

More specifically, replies of involved agent need to reflect thecommunicative discourse of the first, seed message. As a simpleobservation, because the first agent uses Attribution to communicate hisclaims, the other agents have to follow the suite and either providetheir own attributions or attack the validity of attribution of theproponent, or both. To capture a broad variety of features for howcommunicative structure of the seed message needs to be retained inconsecutive messages, pairs of respective CDTs can be learned.

To verify the agreement of a request-response, discourse relations orspeech acts (communicative actions) alone are often insufficient. As canbe seen from the example depicted in FIGS. 11-13, the discoursestructure of interactions between agents and the kind of interactionsare useful. However, the domain of interaction (e.g., military conflictsor politics) or the subjects of these interactions, i.e., the entities,do not need to be analyzed.

Representing Rhetoric Relations and Communicative Actions

In order to compute similarity between abstract structures, twoapproaches are frequently used: (1) representing these structures in anumerical space, and express similarity as a number, which is astatistical learning approach, or (2) using a structural representation,without numerical space, such as trees and graphs, and expressingsimilarity as a maximal common sub-structure. Expressing similarity as amaximal common sub-structure is referred to as generalization.

Learning communicative actions helps express and understand arguments.Computational verb lexicons help support acquisition of entities foractions and provide a rule-based form to express their meanings. Verbsexpress the semantics of an event being described as well as therelational information among participants in that event, and project thesyntactic structures that encode that information. Verbs, and inparticular communicative action verbs, can be highly variable and candisplay a rich range of semantic behaviors. In response, verbclassification helps a learning systems to deal with this complexity byorganizing verbs into groups that share core semantic properties.

VerbNet is one such lexicon, which identifies semantic roles andsyntactic patterns characteristic of the verbs in each class and makesexplicit the connections between the syntactic patterns and theunderlying semantic relations that can be inferred for all members ofthe class. See Karin Kipper, Anna Korhonen, Neville Ryant and MarthaPalmer, Language Resources and Evaluation, Vol. 42, No. 1 (March 2008),at 21. Each syntactic frame, or verb signature, for a class has acorresponding semantic representation that details the semanticrelations between event participants across the course of the event.

For example, the verb amuse is part of a cluster of similar verbs thathave a similar structure of arguments (semantic roles) such as amaze,anger, arouse, disturb, and irritate. The roles of the arguments ofthese communicative actions are as follows: Experiencer (usually, ananimate entity), Stimulus, and Result. Each verb can have classes ofmeanings differentiated by syntactic features for how this verb occursin a sentence, or frames. For example, the frames for amuse are asfollows, using the following key noun phrase (NP), noun (N),communicative action (V), verb phrase (VP), adverb (ADV):

NP V NP. Example: “The teacher amused the children.” Syntax: Stimulus VExperiencer. Clause: amuse(Stimulus, E, Emotion, Experiencer),cause(Stimulus, E), emotional_state(result(E), Emotion, Experiencer).

NP V ADV-Middle. Example: “Small children amuse quickly.” Syntax:Experiencer V ADV. Clause: amuse(Experiencer, Prop):—,property(Experiencer, Prop), adv(Prop).

NP V NP-PRO-ARB. Example “The teacher amused.” Syntax Stimulus V.amuse(Stimulus, E, Emotion, Experiencer): cause(Stimulus, E),emotional_state(result(E), Emotion, Experiencer).

NP.cause V NP. Example “The teacher's dolls amused the children.” syntaxStimulus <+genitive>('s) V Experiencer. amuse(Stimulus, E, Emotion,Experiencer): cause(Stimulus, E),

emotional_state(during(E), Emotion, Experiencer).

NP V NP ADJ. Example “This performance bored me totally.” syntaxStimulus V Experiencer Result. amuse(Stimulus, E, Emotion, Experiencer).cause(Stimulus, E), emotional_state(result(E), Emotion, Experiencer),Pred(result(E), Experiencer).

Communicative actions can be characterized into clusters, for example:

Verbs with Predicative Complements (Appoint, characterize, dub, declare,conjecture, masquerade, orphan, captain, consider, classify), Verbs ofPerception (See, sight, peer).

Verbs of Psychological State (Amuse, admire, marvel, appeal), Verbs ofDesire (Want, long).

Judgment Verbs (Judgment), Verbs of Assessment (Assess, estimate), Verbsof Searching (Hunt, search, stalk, investigate, rummage, ferret), Verbsof Social Interaction (Correspond, marry, meet, battle), Verbs ofCommunication (Transfer(message), inquire, interrogate, tell,manner(speaking), talk, chat, say, complain, advise, confess, lecture,overstate, promise). Avoid Verbs (Avoid), Measure Verbs, (Register,cost, fit, price, bill), Aspectual Verbs (Begin, complete, continue,stop, establish, sustain.

Aspects described herein provide advantages over statistical learningmodels. In contrast to statistical solutions, aspects use aclassification system can provide a verb or a verb-like structure whichis determined to cause the target feature (such as rhetoric agreement).For example, statistical machine learning models express similarity as anumber, which can make interpretation difficult.

Representing Request-Response Pairs

Representing request-response pairs facilitates classification basedoperations based on a pair. In an example, request-response pairs can berepresented as parse thickets. A parse thicket is a representation ofparse trees for two or more sentences with discourse-level relationshipsbetween words and parts of the sentence in one graph. See Galitsky 2015.Topical similarity between question and answer can expressed as commonsub-graphs of parse thickets. The higher the number of common graphnodes, the higher the similarity.

FIG. 14 illustrates parse thickets in accordance with an aspect. FIG. 14depicts parse thicket 1400 including a parse tree for a request 1401,and a parse tree for a corresponding response 1402.

Parse tree 1401 represents the question “I just had a baby and it looksmore like the husband I had my baby with. However it does not look likeme at all and I am scared that he was cheating on me with another ladyand I had her kid. This child is the best thing that has ever happenedto me and I cannot imagine giving my baby to the real mom.”

Response 1402 represents the response “Marital therapists advise ondealing with a child being born from an affair as follows. One option isfor the husband to avoid contact but just have the basic legal andfinancial commitments. Another option is to have the wife fully involvedand have the baby fully integrated into the family just like a childfrom a previous marriage.”

FIG. 14 represents a greedy approach to representing linguisticinformation about a paragraph of text. The straight edges of this graphare syntactic relations, and curvy arcs are discourse relations, such asanaphora, same entity, sub-entity, rhetoric relation and communicativeactions. The solid arcs are for same entity/sub-entity/anaphorarelations, and the dotted arcs are for rhetoric relations andcommunicative actions. Oval labels in straight edges denote thesyntactic relations. Lemmas are written in the boxes for the nodes, andlemma forms are written on the right side of the nodes.

Parse thicket 1400 includes much richer information than just acombination of parse trees for individual sentences. Navigation throughthis graph along the edges for syntactic relations as well as arcs fordiscourse relations allows to transform a given parse thicket intosemantically equivalent forms for matching with other parse thickets,performing a text similarity assessment task. To form a complete formalrepresentation of a paragraph, as many links as possible are expressed.Each of the discourse arcs produces a pair of thicket phrases that canbe a potential match.

Topical similarity between the seed (request) and response is expressedas common sub-graphs of parse thickets. They are visualized as connectedclouds. The higher the number of common graph nodes, the higher thesimilarity. For rhetoric agreement, common sub-graph does not have to belarge as it is in the given text. However, rhetoric relations andcommunicative actions of the seed and response are correlated and acorrespondence is required.

Generalization for Communicative Actions

A similarity between two communicative actions A₁ and A₂ is defined as aan abstract verb which possesses the features which are common betweenA₁ and A₂. Defining a similarity of two verbs as an abstract verb-likestructure supports inductive learning tasks, such as a rhetoricagreement assessment. In an example, a similarity between the followingtwo common verbs, agree and disagree, can be generalized as follows:agree{circumflex over ( )}disagree=verb(Interlocutor, Proposed_action,Speaker), where Interlocution is the person who proposed theProposed_action to the Speaker and to whom the Speaker communicatestheir response. Proposed_action is an action that the Speaker wouldperform if they were to accept or refuse the request or offer, and TheSpeaker is the person to whom a particular action has been proposed andwho responds to the request or offer made.

In a further example, a similarity between verbs agree and explain isrepresented as follows: agree{circumflex over( )}explain=verb(Interlocutor, *, Speaker). The subjects ofcommunicative actions are generalized in the context of communicativeactions and are not be generalized with other “physical” actions. Hence,aspects generalize individual occurrences of communicative actionstogether with corresponding subjects.

Additionally, sequences of communicative actions representing dialogscan be compared against other such sequences of similar dialogs. In thismanner, the meaning of an individual communicative action as well as thedynamic discourse structure of a dialogue is (in contrast to its staticstructure reflected via rhetoric relations) is represented. Ageneralization is a compound structural representation that happens ateach level. Lemma of a communicative action is generalized with lemma,and its semantic role are generalized with respective semantic role.

Communicative actions are used by text authors to indicate a structureof a dialogue or a conflict. See Searle, J. R. 1969, Speech acts: anessay in the philosophy of language. London: Cambridge University Press.Subjects are generalized in the context of these actions and are notgeneralized with other “physical” actions. Hence, the individualoccurrences of communicative actions together are generalized with theirsubjects, as well as their pairs, as discourse “steps.”

Generalization of communicative actions can also be thought of from thestandpoint of matching the verb frames, such as VerbNet. Thecommunicative links reflect the discourse structure associated withparticipation (or mentioning) of more than a single agent in the text.The links form a sequence connecting the words for communicative actions(either verbs or multi-words implicitly indicating a communicativeintent of a person).

Communicative actions include an actor, one or more agents being actedupon, and the phrase describing the features of this action. Acommunicative action can be described as a function of the form: verb(agent, subject, cause), where verb characterizes some type ofinteraction between involved agents (e.g., explain, confirm, remind,disagree, deny, etc.), subject refers to the information transmitted orobject described, and cause refers to the motivation or explanation forthe subject.

A scenario (labeled directed graph) is a sub-graph of a parse thicketG=(V,A), where V={action₁, action₂ . . . action_(n)} is a finite set ofvertices corresponding to communicative actions, and A is a finite setof labeled arcs (ordered pairs of vertices), classified as follows:

Each arc action_(i), action_(j)∈A_(sequence) corresponds to a temporalprecedence of two actions v_(i), ag_(i), s_(i), c_(i) and v_(j), ag_(j),s_(j), c_(j) that refer to the same subject, e.g., s_(j)=s_(i) ordifferent subjects. Each arc action_(i), action_(j)∈A_(cause)corresponds to an attack relationship between action_(i) and action_(j)indicating that the cause of action_(i) in conflict with the subject orcause of action_(j).

Subgraphs of parse thickets associated with scenarios of interactionbetween agents have some distinguishing features. For example, (1) allvertices are ordered in time, so that there is one incoming arc and oneoutgoing arc for all vertices (except the initial and terminalvertices), (2) for A_(sequence) arcs, at most one incoming and only oneoutgoing arc are admissible, and (3) for A_(cause) arcs, there can bemany outgoing arcs from a given vertex, as well as many incoming arcs.The vertices involved may be associated with different agents or withthe same agent (i.e., when he contradicts himself). To computesimilarities between parse thickets and their communicative action,induced subgraphs, the sub-graphs of the same configuration with similarlabels of arcs and strict correspondence of vertices are analyzed.

The following similarities exist by analyzing the arcs of thecommunicative actions of a parse thicket: (1) one communicative actionfrom with its subject from T1 against another communicative action withits subject from T2 (communicative action arc is not used), and (2) apair of communicative actions with their subjects from T1 compared toanother pair of communicative actions from T2 (communicative action arcsare used).

Generalizing two different communicative actions is based on theirattributes. See (Galitsky et al 2013). As can be seen in the examplediscussed with respect to FIG. 14, one communicative action from T1,cheating(husband, wife, another lady) can be compared with a second fromT2, avoid(husband, contact(husband, another lady)). A generalizationresults in communicative action(husband, *) which introduces aconstraint on A in the form that if a given agent (=husband) ismentioned as a subject of CA in Q, he(she) should also be a subject of(possibly, another) CA in A. Two communicative actions can always begeneralized, which is not the case for their subjects: if theirgeneralization result is empty, the generalization result ofcommunicative actions with these subjects is also empty.

Generalization of RST Relations

Some relations between discourse trees can be generalized, such as arcsthat represent the same type of relation (presentation relation, such asantithesis, subject matter relation, such as condition, and multinuclearrelation, such as list) can be generalized. A nucleus or a situationpresented by a nucleus is indicated by “N.” Satellite or situationspresented by a satellite, are indicated by “S.” “W” indicates a writer.“R” indicates a reader (hearer). Situations are propositions, completedactions or actions in progress, and communicative actions and states(including beliefs, desires, approve, explain, reconcile and others).Generalization of two RST relations with the above parameters isexpressed as:

rst1(N1, S1, W1, R1){circumflex over ( )}rst2 (N2, S2, W2, R2)=

(rst1{circumflex over ( )}rst2)(N1{circumflex over ( )}N2, S1{circumflexover ( )}S2, W1{circumflex over ( )}W2, R1{circumflex over ( )}R2).

The texts in N1, S1, W1, R1 are subject to generalization as phrases.For example, rst1{circumflex over ( )}rst2 can be generalized asfollows: (1) if relation_type(rst1)!=relation_type(rst2) then ageneralization is empty. (2) Otherwise, the signatures of rhetoricrelations are generalized as sentences: sentence(N1, S1, W1, R1) Asentence(N2, S2, W2, R2). See Iruskieta, Mikel, Iria da Cunha and MaiteTaboada. A qualitative comparison method for rhetorical structures:identifying different discourse structures in multilingual corpora. LangResources & Evaluation. June 2015, Volume 49, Issue 2.

For example, the meaning of rst−background{circumflex over( )}rst−enablement=(S increases the ability of R to comprehend anelement in N){circumflex over ( )}(R comprehending S increases theability of R to perform the action in N)=increase-VB the-DT ability-NNof-IN R-NN to-IN.

Because the relations rst−background{circumflex over ( )}rst−enablementdiffer, the RST relation part is empty. The expressions that are theverbal definitions of respective RST relations are then generalized. Forexample, for each word or a placeholder for a word such as an agent,this word (with its POS) is retained if the word the same in each inputphrase or remove the word if the word is different between thesephrases. The resultant expression can be interpreted as a common meaningbetween the definitions of two different RST relations, obtainedformally.

Two arcs between the question and the answer depicted in FIG. 14 showthe generalization instance based on the RST relation “RST-contrast”.For example, “I just had a baby” is a RST-contrast with “it does notlook like me,” and related to “husband to avoid contact” which is aRST-contrast with “have the basic legal and financial commitments.” Ascan be seen, the answer need not have to be similar to the verb phraseof the question but the rhetoric structure of the question and answerare similar. Not all phrases in the answer must match phrases inquestion. For example, the phrases that do not match have certainrhetoric relations with the phrases in the answer which are relevant tophrases in question.

Building a Communicative Discourse Tree

FIG. 15 illustrates an exemplary process for building a communicativediscourse tree in accordance with an aspect. Rhetoric classificationapplication 102 can implement process 1500. As discussed, communicativediscourse trees enable improved search engine results.

At block 1501, process 1500 involves accessing a sentence comprisingfragments. At least one fragment includes a verb and words and each wordincludes a role of the words within the fragment, and each fragment isan elementary discourse unit. For example, rhetoric classificationapplication 102 accesses a sentence such as “Rebels, the self-proclaimedDonetsk People's Republic, deny that they controlled the territory fromwhich the missile was allegedly fired” as described with respect to FIG.13.

Continuing the example, rhetoric classification application 102determines that the sentence includes several fragments. For example, afirst fragment is “rebels . . . deny.” A second fragment is “that theycontrolled the territory.” A third fragment is “from which the missilewas allegedly fired.” Each fragment includes a verb, for example, “deny”for the first fragment and “controlled” for the second fragment.Although, a fragment need not include a verb.

At block 1502, process 1500 involves generating a discourse tree thatrepresents rhetorical relationships between the sentence fragments. Thediscourse tree including nodes, each nonterminal node representing arhetorical relationship between two of the sentence fragments and eachterminal node of the nodes of the discourse tree is associated with oneof the sentence fragments.

Continuing the example, rhetoric classification application 102generates a discourse tree as shown in FIG. 13. For example, the thirdfragment, “from which the missile was allegedly fired” elaborates on“that they controlled the territory.” The second and third fragmentstogether relate to attribution of what happened, i.e., the attack cannothave been the rebels because they do not control the territory.

At block 1503, process 1500 involves accessing multiple verb signatures.For example, rhetoric classification application 102 accesses a list ofverbs, e.g., from VerbNet. Each verb matches or is related to the verbof the fragment. For example, the for the first fragment, the verb is“deny.” Accordingly, rhetoric classification application 102 accesses alist of verb signatures that relate to the verb deny.

As discussed, each verb signature includes the verb of the fragment andone or more of thematic roles. For example, a signature includes one ormore of noun phrase (NP), noun (N), communicative action (V), verbphrase (VP), or adverb (ADV). The thematic roles describing therelationship between the verb and related words. For example “theteacher amused the children” has a different signature from “smallchildren amuse quickly.” For the first fragment, the verb “deny,”rhetoric classification application 102 accesses a list of frames, orverb signatures for verbs that match “deny.” The list is “NP V NP to beNP,” “NP V that S” and “NP V NP.”

Each verb signature includes thematic roles. A thematic role refers tothe role of the verb in the sentence fragment. Rhetoric classificationapplication 102 determines the thematic roles in each verb signature.Example thematic roles include actor, agent, asset, attribute,beneficiary, cause, location destination source, destination, source,location, experiencer, extent, instrument, material and product,material, product, patient, predicate, recipient, stimulus, theme, time,or topic.

At block 1504, process 1500 involves determining, for each verbsignature of the verb signatures, a number of thematic roles of therespective signature that match a role of a word in the fragment. Forthe first fragment, rhetorical classification application 102 determinesthat the verb “deny” has only three roles, “agent”, “verb” and “theme.”

Representing a Request-Response

Request-response pairs can be analyzed alone or as pairs. In an example,request-response pairs can be chained together. In a chain, rhetoricagreement is expected to hold not only between consecutive members butalso triples and four-tuples. A discourse tree can be constructed for atext expressing a sequence of request-response pairs. For example, inthe domain of customer complaints, request and response are present inthe same text, from the viewpoint of a complainant. Customer complainttext can to be split into request and response text portions and thenform the positive and negative dataset of pairs. In an example, all textfor the proponent and all text for the opponent is combined. The firstsentence of each paragraph below will form the Request part (which willinclude three sentences) and second sentence of each paragraph will formthe Response part (which will also include three sentences in thisexample).

FIG. 16 illustrates a discourse tree and scenario graph in accordancewith an aspect. FIG. 16 depicts discourse tree 1601 and scenario graph1602. Discourse tree 1601 corresponds to the following three sentences:

(1) I explained that my check bounced (I wrote it after I made adeposit). A customer service representative accepted that it usuallytakes some time to process the deposit.

(2) I reminded that I was unfairly charged an overdraft fee a month agoin a similar situation. They denied that it was unfair because theoverdraft fee was disclosed in my account information.

(3) I disagreed with their fee and wanted this fee deposited back to myaccount. They explained that nothing can be done at this point and thatI need to look into the account rules closer.

As can be seen by the discourse tree in FIG. 16, determining whether thetext represents an interaction or a description can be hard to judge.Hence, by analyzing the arcs of communicative actions of a parsethicket, implicit similarities between texts can be found. For example,in general terms:

(1) one communicative actions from with its subject from a first treeagainst another communicative action with its subject from a second tree(communicative action arc is not used).

(2) a pair of communicative actions with their subjects from a firsttree against another pair of communicative actions from a second tree(communicative action arcs are used).

For example, in the previous example, the generalization ofcheating(husband, wife, another lady){circumflex over ( )}avoid(husband,contact(husband, another lady)) provides us communicativeaction(husband, *) which introduces a constraint on A in the form thatif a given agent (=husband) is mentioned as a subject of CA in Q,he(she) should also be a subject of (possibly, another) CA in A.

To handle meaning of words expressing the subjects of CAs, a word can beapplied to a vector model such as the “word2vector” model. Morespecifically, to compute generalization between the subjects ofcommunicative actions, the following rule can be used: ifsubject1=subject2, subject1{circumflex over ( )}subject2=<subject1,POS(subject1), 1>. Here subject remains and score is 1. Otherwise, ifthe subjects have the same part-of-speech (POS), thensubject1{circumflex over ( )}subject2=<*, POS(subject1),word2vecDistance(subject1{circumflex over ( )}subject2)>. ‘*’ denotesthat lemma is a placeholder, and the score is a word2vec distancebetween these words. If POS is different, generalization is an emptytuple and may not be further generalized.

Classification Settings for Request-Response Pairs

In a conventional search, as a baseline, the match between requestresponse pairs can be measured in terms of keyword statistics such asshort for term frequency-inverse document frequency (TF*IDF). To improvesearch relevance, this score is augmented by item popularity, itemlocation or taxonomy-based score (Galitsky 2015). Search can also beformulated as a passage re-ranking problem in machine learningframework. The feature space includes request-response pairs aselements, and a separation hyper-plane splits this feature space intocorrect and incorrect pairs. Hence a search problem can be formulated ina local way, as similarity between Req and Resp, or in a global,learning way, via similarity between request-response pairs.

Other methods are possible for determining a match between request andresponse. In a first example, rhetoric classification application 102extracts features for Req and Resp and compares the features as a count,introducing a scoring function such that a score would indicate a class(low score for incorrect pairs, high score for correct ones).

In a second example, rhetoric classification application 102 comparesrepresentations for Req and Resp against each other, and assigns a scorefor the comparison result. Analogously, the score will indicate a class.

In a third example, rhetoric classification application 102 builds arepresentation for a pair Req and Resp, <Req, Resp> as elements oftraining set. Rhetoric classification application 102 then performslearning in the feature space of all such elements <Req, Resp>.

FIG. 17 illustrates forming a request-response pair in accordance withan aspect. FIG. 17 depicts request-response pair 1701, request tree (orobject) 1702, and response tree 1703. To form a <Req, Resp> object, therhetoric classification application 102 combines the discourse tree forthe request and the discourse tree for the response into a single treewith the root RR. The rhetoric classification application 102 thenclassifies the objects into correct (with high agreement) and incorrect(with low agreement) categories.

Nearest Neighbor Graph-Based Classification

Once a CDT is built, in order to identify an argument in text, rhetoricclassification application 102 compute the similarity compared to CDTsfor the positive class and verify that it is lower to the set of CDTsfor its negative class. Similarity between CDT is defined by means ofmaximal common sub-CDTs.

In an example, an ordered set G of CDTs(V,E) with vertex- andedge-labels from the sets (Λ_(ζ),

) and (Λ_(E),

) is constructed. A labeled CDT Γ from G is a pair of pairs of the form((V,l),(E,b)), where V is a set of vertices, E is a set of edges, l:V→Λ_(ζ) is a function assigning labels to vertices, and b: E→Λ_(E) is afunction assigning labels to edges. Isomorphic trees with identicallabeling are not distinguished.

The order is defined as follows: For two CDTs Γ₁:=((V₁,l₁),(E₁,b₁)) andΓ₂:=((V₂,l₂),(E₂,b₂)) from G, then that Γ₁ dominates Γ₂ or Γ₂≤Γ₁ (or Γ₂is a sub-CDT of Γ₁) if there exists a one-to-one mapping φ: V₂→V₁ suchthat it (1) respects edges: (v,w)∈E₂ ⇒(φ(v), φ(w))∈E₁, and (2) fitsunder labels: l₂(v)

l₁(φ(v)), (v,w)∈E₂ ⇒b₂(v,w)

b₁(φ(v), φ(w)).

This definition takes into account the calculation of similarity(“weakening”) of labels of matched vertices when passing from the“larger” CDT G₁ to “smaller” CDT G₂.

Now, similarity CDT Z of a pair of CDTs X and Y, denoted by X{circumflexover ( )}Y=Z, is the set of all inclusion-maximal common sub-CDTs of Xand Y, each of them satisfying the following additional conditions (1)to be matched, two vertices from CDTs X and Y must denote the same RSTrelation; and (2) each common sub-CDT from Z contains at least onecommunicative action with the same VerbNet signature as in X and Y.

This definition is easily extended to finding generalizations of severalgraphs. The subsumption order μ on pairs of graph sets X and Y isnaturally defined as XμY:=X*Y=X.

FIG. 18 illustrates a maximal common sub-communicative discourse tree inaccordance with an aspect. Notice that the tree is inverted and thelabels of arcs are generalized: Communicative action site( ) isgeneralized with communicative action say( ). The first (agent) argumentof the former CA committee is generalized with the first argument of thelatter CA Dutch. The same operation is applied to the second argumentsfor this pair of CAs: investigator{circumflex over ( )}evidence.

CDT U belongs to a positive class such that (1) U is similar to (has anonempty common sub-CDT) with a positive example R⁺ and (2) for anynegative example R⁻, if U is similar to R⁻ (i.e., U*R⁻≠Ø) thenU*R⁻μU*R⁺.

This condition introduces the measure of similarity and says that to beassigned to a class, the similarity between the unknown CDT U and theclosest CDT from the positive class should be higher than the similaritybetween U and each negative example. Condition 2 implies that there is apositive example R⁺ such that for no R⁻ one has U*R⁺μR⁻, i.e., there isno counterexample to this generalization of positive examples.

Thicket Kernel Learning for CDT

Tree Kernel learning for strings, parse trees and parse thickets is awell-established research area these days. The parse tree kernel countsthe number of common sub-trees as the discourse similarity measurebetween two instances. Tree kernel has been defined for DT by Joty,Shafiq and A. Moschitti. Discriminative Reranking of Discourse ParsesUsing Tree Kernels. Proceedings of EMNLP. (2014). See also Wang, W., Su,J., & Tan, C. L. (2010). Kernel Based Discourse Relation Recognitionwith Temporal Ordering Information. In Proceedings of the 48th AnnualMeeting of the Association for Computational Linguistics. (using thespecial form of tree kernels for discourse relation recognition). Athicket kernel is defined for a CDT by augmenting a DT kernel by theinformation on communicative actions.

A CDT can be represented by a vector V of integer counts of eachsub-tree type (without taking into account its ancestors):

V (T)=(# of subtrees of type 1, . . . ,# of subtrees of type I, . . . ,#of subtrees of type n). This results in a very high dimensionality sincethe number of different sub-trees is exponential in its size. Thus, itis computational infeasible to directly use the feature vector Ø (T). Tosolve the computational issue, a tree kernel function is introduced tocalculate the dot product between the above high dimensional vectorsefficiently. Given two tree segments CDT1 and CDT2, the tree kernelfunction is defined:K (CDT1, CDT2)=<V (CDT1), V (CDT2)>=Σi V (CDT1)[i], V (CDT2)[i]=Σn1Σn2Σi Ii(n1)*Ii(n2) wheren1∈N1, n2∈N2 where N1 and N2 are the sets of all nodes in CDT1 and CDT2,respectively;Ii (n) is the indicator function.Ii (n)={1 iff a subtree of type i occurs with root at node; 0otherwise}. K (CDT1, CDT2) is an instance of convolution kernels overtree structures (Collins and Duffy, 2002) and can be computed byrecursive definitions:Δ (n1, n2)=ΣI Ii(n1)*Ii(n2)Δ (n1, n2)=0 if n1 and n2 are assigned the same POS tag or theirchildren are different subtrees.Otherwise, if both n1 and n2 are POS tags (are pre-terminal nodes) thenΔ (n1, n2)=1×λ;Otherwise, Δ (n1, n2)=λΠ_(j=1) ^(nc(n)1)(1+Δ(ch(n1, j), ch(n2, j)))where ch(n,j) is the jth child of node n, nc(n₁) is the number of thechildren of n₁, and (0<λ<1) is the decay factor in order to make thekernel value less variable with respect to the sub-tree sizes. Inaddition, the recursive rule (3) holds because given two nodes with thesame children, one can construct common sub-trees using these childrenand common sub-trees of further offspring. The parse tree kernel countsthe number of common sub-trees as the syntactic similarity measurebetween two instances.

FIG. 19 illustrates a tree in a kernel learning format for acommunicative discourse tree in accordance with an aspect.

The terms for Communicative Actions as labels are converted into treeswhich are added to respective nodes for RST relations. For texts forEDUs as labels for terminal nodes only the phrase structure is retained.The terminal nodes are labeled with the sequence of phrase types insteadof parse tree fragments.

If there is a rhetoric relation arc from a node X to a terminal EDU nodeY with label A(B, C(D)), then the subtree A−B→(C−D) is appended to X.

Implementation of the Rhetoric Agreement Classifier

Rhetoric agreement classifier 120 can determine the complementaritybetween two sentences, such as a question and an answer, by usingcommunicative discourse trees. FIG. 20 illustrates an exemplary processused to implement a rhetoric agreement classifier in accordance with anaspect. FIG. 20 depicts process 2000, which can be implemented byrhetoric classification application 102. As discussed, rhetoricagreement classifier 120 is trained with training data 125.

Rhetoric agreement classifier 120 determines a communicative discoursetree for both question and answer. For example, rhetoric agreementclassifier 120 constructs question communicative discourse tree 110 froma question such as question 171 or question 130, and answercommunicative discourse tree 111 from a candidate answer.

At block 2001, process 2000 involves determining, for a questionsentence, a question communicative discourse tree including a questionroot node. A question sentence can be an explicit question, a request,or a comment. Rhetoric classification application 102 creates questioncommunicative discourse tree 110 from question 130. Using the examplediscussed in relation to FIGS. 13 and 15, an example question sentenceis “are rebels responsible for the downing of the flight.” Rhetoricclassification application 102 can use process 1500 described withrespect to FIG. 15. The example question has a root node of “elaborate.”

At block 2002, process 2000 involves determining, for an answersentence, a second communicative discourse tree, wherein the answercommunicative discourse tree includes an answer root node. Continuingthe above example, rhetoric classification application 102 creates ancommunicative discourse tree 111, as depicted in FIG. 13, which also hasa root node “elaborate.”

At block 2003, process 2000 involves associating the communicativediscourse trees by identifying that the question root node and theanswer root node are identical. Rhetoric classification application 102determines that the question communicative discourse tree 110 and answercommunicative discourse tree 111 have an identical root node. Theresulting associated communicative discourse tree is depicted in FIG. 17and can be labeled as a “request-response pair.”

At block 2004, process 2000 involves computing a level ofcomplementarity between the question communicative discourse tree andthe answer communicative discourse tree by applying a predictive modelto the merged discourse tree.

The rhetoric agreement classifier uses machine learning techniques. Inan aspect, the rhetoric classification application 102 trains and usesrhetoric agreement classifier 120. For example, rhetoric classificationapplication 102 defines positive and negative classes ofrequest-response pairs. The positive class includes rhetorically correctrequest-response pairs and the negative class includes relevant butrhetorically foreign request-response pairs.

For each request-response pair, the rhetoric classification application102 builds a CDT by parsing each sentence and obtaining verb signaturesfor the sentence fragments.

Rhetoric classification application 102 provides the associatedcommunicative discourse tree pair to rhetoric agreement classifier 120.Rhetoric agreement classifier 120 outputs a level of complementarity.

At block 2005, process 2000 involves responsive to determining that thelevel of complementarity is above a threshold, identifying the questionand answer sentences as complementary. Rhetoric classificationapplication 102 can use a threshold level of complementarity todetermine whether the question-answer pair is sufficientlycomplementary. For example, if a classification score is greater than athreshold, then rhetoric classification application 102 can output theanswer as answer 172 or answer 150. Alternatively, rhetoricclassification application 102 can discard the answer and access answerdatabase 105 or a public database for another candidate answer andrepeat process 2000 as necessary.

In an aspect, the rhetoric classification application 102 obtainsco-references. In a further aspect, the rhetoric classificationapplication 102 obtains entity and sub-entity, or hyponym links. Ahyponym is a word of more specific meaning than a general orsuperordinate term applicable to the word. For example, “spoon” is ahyponym of “cutlery.”

In another aspect, rhetoric classification application 102 appliesthicket kernel learning to the representations. Thicket kernel learningcan take place in place of classification-based learning describedabove, e.g., at block 2004. The rhetoric classification application 102builds a parse thicket pair for the parse tree of the request-responsepair. The rhetoric classification application 102 applies discourseparsing to obtain a discourse tree pair for the request-response pair.The rhetoric classification application 102 aligns elementary discourseunits of the discourse tree request-response and the parse treerequest-response. The rhetoric classification application 102 merges theelementary discourse units of the discourse tree request-response andthe parse tree request-response.

In an aspect, rhetoric classification application 102 improves the textsimilarity assessment by word2vector model.

In a further aspect, rhetoric classification application 102 sends asentence that corresponds to the question communicative discourse tree110 or a sentence that corresponds to the answer communicative discoursetree to a device such as mobile device 170. Outputs from rhetoricclassification application 102 can be used as inputs to search queries,database lookups, or other systems. In this manner, rhetoricclassification application 102 can integrate with a search enginesystem.

FIG. 21 illustrates a chat bot commenting on a posting in accordancewith an aspect. FIG. 21 depicts chat 2100, user messages 2101-2104, andagent response 2105. Agent response 2105 can be implemented by therhetoric classification application 102. As shown, agent response 2105has identified a suitable answer to the thread of messages 2101-2104.

FIG. 22 illustrates a chat bot commenting on a posting in accordancewith an aspect. FIG. 22 depicts chat 2200, user messages 2201-2205, andagent response 2206. FIG. 22 depicts three messages from user 1,specifically 2201, 2203, and 2205, and two messages from user 2,specifically 2202 and 2204. Agent response 2206 can be implemented bythe rhetoric classification application 102. As shown, agent response2106 has identified a suitable answer to the thread of messages2201-2204.

The features depicted in FIGS. 21 and 22 can be implemented by rhetoricclassification computing device 101, or by a device that providesquestion 130 to rhetoric classification computing device 101 andreceives answer 150 from rhetoric classification computing device 101.

Additional Rules for RR Agreement and RR Irrationality

The following are the examples of structural rules which introduceconstraint to enforce RR agreement:

1. Both Req and Resp have the same sentiment polarity (If a request ispositive the response should be positive as well, and other way around.

2. Both Req and Resp have a logical argument.

Under rational reasoning, Request and Response will fully agree: arational agent will provide an answer which will be both relevant andmatch the question rhetoric. However, in the real world not allresponses are fully rational. The body of research on Cognitive biasesexplores human tendencies to think in certain ways that can lead tosystematic deviations from a standard of rationality or good judgment.

The correspondence bias is the tendency for people to over-emphasizepersonality-based explanations for behaviors observed in others,responding to questions. See Baumeister, R. F. & Bushman, B. J. Socialpsychology and human nature: International Edition. (2010). At the sametime, those responding queries under-emphasize the role and power ofsituational influences on the same behavior.

Confirmation bias, the inclination to search for or interpretinformation in a way that confirms the preconceptions of those answeringquestions. They may discredit information that does not support theirviews. The confirmation bias is related to the concept of cognitivedissonance. Whereby, individuals may reduce inconsistency by searchingfor information which re-confirms their views.

Anchoring leads to relying too heavily, or “anchor”, on one trait orpiece of information when making decisions.

Availability heuristic makes us overestimate the likelihood of eventswith greater “availability” in memory, which can be influenced by howrecent the memories are or how unusual or emotionally charged they maybe.

According to Bandwagon effect, people answer questions believing inthings because many other people do (or believe) the same.

Belief bias is an effect where someone's evaluation of the logicalstrength of an argument is biased by the believability of theconclusion.

Bias blind spot is the tendency to see oneself as less biased than otherpeople, or to be able to identify more cognitive biases in others thanin oneself.

Evaluation

A first domain of test data is derived from question-answer pairs fromYahoo! Answers. set of question-answer pairs with broad topics. Out ofthe set of 4.4 million user questions, 20000 are selected that eachinclude more than two sentences. Answers for most questions are fairlydetailed so no filtering was applied to answers. There are multipleanswers per questions and the best one is marked. We consider the pairQuestion-Best Answer as an element of the positive training set andQuestion-Other-Answer as the one of the negative training set. To derivethe negative set, we either randomly select an answer to a different butsomewhat related question, or formed a query from the question andobtained an answer from web search results.

Our second dataset includes the social media. We extractedRequest-Response pairs mainly from postings on Facebook. We also used asmaller portion of LinkedIn.com and vk.com conversations related toemployment. In the social domains the standards of writing are fairlylow. The cohesiveness of text is very limited and the logical structureand relevance frequently absent. The authors formed the training setsfrom their own accounts and also public Facebook accounts available viaAPI over a number of years (at the time of writing Facebook API forgetting messages is unavailable). In addition, we used 860 email threadsfrom Enron dataset. Also, we collected the data of manual responses topostings of an agent which automatically generates posts on behalf ofhuman users-hosts. See Galitsky B., Dmitri Ilvovsky, Nina Lebedeva andDaniel Usikov. Improving Trust in Automation of Social Promotion. AAAISpring Symposium on The Intersection of Robust Intelligence and Trust inAutonomous Systems Stanford Calif. 2014. (“Galitsky 2014”). We formed4000 pairs from the various social network sources.

The third domain is customer complaints. In a typical complaint adissatisfied customer describes his problems with products and serviceas well as the process for how he attempted to communicate theseproblems with the company and how they responded. Complaints arefrequently written in a biased way, exaggerating product faults andpresenting the actions of opponents as unfair and inappropriate. At thesame time, the complainants try to write complaints in a convincing,coherent and logically consistent way (Galitsky 2014); thereforecomplaints serve as a domain with high agreement between requests andresponse. For the purpose of assessing agreement between user complaintand company response (according to how this user describes it) wecollected 670 complaints from planetfeedback.com over 10 years.

The fourth domain is interview by journalist. Usually, the wayinterviews are written by professional journalists is such that thematch between questions and answers is very high. We collected 1200contributions of professional and citizen journalists from such sourcesas datran.com, allvoices.com, huffingtonpost.com and others.

To facilitate data collection, we designed a crawler which searched aspecific set of sites, downloaded web pages, extracted candidate textand verified that it adhered to a question-or-request vs responseformat. Then the respective pair of text is formed. The search isimplemented via Bing Azure Search Engine API in the Web and Newsdomains.

Recognizing valid and invalid answers

Answer classification accuracies are shown in Table 1. Each rowrepresents a particular method; each class of methods in shown in grayedareas.

TABLE 1 Evaluation results Source Conversation on Customer Interviews byEvaluation Yahoo! Answers Social Networks complaints Journalists SettingP R F1 P R F1 P R F1 P R F1 Types and counts 55.2 52.9 54.03 51.5 52.451.95 54.2 53.9 54.05 53 55.5 54.23 for rhetoric relations of Req andResp Entity-based 63.1 57.8 6.33 51.6 58.3 54.7 48.6 57.0 52.45 59.257.9 53.21 alignment of DT of Req-Resp Maximal common 67.3 64.1 65.6670.2 61.2 65.4 54.6 60.0 57.16 80.2 69.8 74.61 sub-DT for Req and RespMaximal common 68.1 67.2 67.65 68.0 63.8 65.83 58.4 62.8 60.48 77.6 67.672.26 sub-CDT for Req and Resp SVM TK for Parse 66.1 63.8 64.93 69.364.4 66.8 46.7 61.9 53.27 78.7 66.8 72.24 Trees of individual sentencesSVM TK for RST 75.8 74.2 74.99 72.7 77.7 75.11 63.5 74.9 68.74 75.7 84.579.83 and CA (full parse trees) SVM TK for RR- 76.5 77 76.75 74.4 71.873.07 64.2 69.4 66.69 82.5 69.4 75.4 DT SVM TK for RR- 80.3 78.3 79.2978.6 82.1 80.34 59.5 79.9 68.22 82.7 80.9 81.78 CDT SVM TK for RR- 78.376.9 77.59 67.5 69.3 68.38 55.8 65.9 60.44 76.5 74.0 75.21 CDT +sentiment + argumentation features

One can see that the highest accuracy is achieved in journalism andcommunity answers domain and the lowest in customer complaints andsocial networks. We can conclude that the higher is the achievedaccuracy having the method fixed, the higher is the level of agreementbetween Req and Resp and correspondingly the higher the responder'scompetence.

Deterministic family of approaches (middle two rows, local RRsimilarity-based classification) performs about 9% below SVM TK whichindicates that similarity between Req and Resp is substantially lessimportant than certain structures of RR pairs indicative of an RRagreement. It means that agreement between Req and Resp cannot beassessed on the individual basis: if we demand DT(Req) be very similarto DT(Resp) we will get a decent precision but extremely low recall.Proceeding from DT to CDT helps by 1-2% only, since communicativeactions play a major role in neither composing a request nor forming aresponse.

For statistical family of approaches (bottom 5 rows, tree kernels), therichest source of discourse data (SVM TK for RR-DT) gives the highestclassification accuracy, almost the same as the RR similarity-basedclassification. Although SVM TK for RST and CA (full parse trees)included more linguistic data, some part of it (most likely, syntactic)is redundant and gives lower results for the limited training set. Usingadditional features under TK such as sentiment and argumentation doesnot help either: most likely, these features are derived from RR-CDTfeatures and do not contribute to classification accuracy on their own.

Employing TK family of approaches based on CDT gives us the accuracycomparable to the one achieved in classifying DT as correct andincorrect, the rhetoric parsing tasks where the state-of-the-art systemsmeet a strong competition over last few years and derived over 80%accuracy.

Direct analysis approaches in the deterministic family perform ratherweakly, which means that a higher number and a more complicatedstructure of features is required: just counting and taking into accounttypes of rhetoric relations is insufficient to judge on how RR agreewith each other. If two RR pairs have the same types and counts ofrhetoric relations and even communicative actions they can still belongto opposite RR agreement classes in the majority of cases.

Nearest-pair neighbor learning for CDT achieves lower accuracy than SVMTK for CDT, but the former gives interesting examples of sub-trees whichare typical for argumentation, and the ones which are shared among thefactoid data. The number of the former groups of CDT sub-trees isnaturally significantly higher. Unfortunately SVM TK approach does nothelp to explain how exactly the RR agreement problem is solved: it onlygives final scoring and class labels. It is possible but infrequent toexpress a logical argument in a response without communicative actions(this observation is backed up by our data).

Measuring RR Agreement in Evaluation Domains

From the standpoint of evaluation of recognition accuracy, we obtainedthe best method in the previous subsection. Now, having this methodfixed, we will measure RR agreements in our evaluation domains. We willalso show how the general, total agreement delivered by the best methodis correlated with individual agreement criteria such as sentiment,logical argumentation, topics and keyword relevance. Once we use ourbest approach (SVM TK for RR-CDT) for labeling training set, the size ofit can grow dramatically and we can explore interesting properties of RRagreement in various domains. We will discover the contribution of anumber of intuitive features of RR agreement on a larger dataset thanthe previous evaluation.

In this Subsection we intend to demonstrate that the RR pair validityrecognition framework can serve as a measure of agreement between anarbitrary request and response. Also, this recognition framework canassess how strongly various features are correlated with RR pairvalidity.

From the evaluation of recognition accuracy, we obtained the best methodto recognize of the RR pair is valid or not. Now, having thisrecognition method fixed, we will measure RR agreements in ourevaluation domains, and will also estimate how a general, totalagreement delivered by the best method is correlated with individualagreement criteria such as sentiment, logical argumentation, topics andkeyword relevance. Once we use our best approach (SVM TK for RR-CDT) forlabeling training set, the size of it can grow dramatically and we canexplore interesting properties of RR agreement in various domains. Wewill discover on a larger dataset than the previous evaluation, thecontribution of a number of intuitive features of RR agreement. We willmeasure this agreement on a feature-by-feature basis, on a positivetraining dataset of above evaluation only, as a recognition precision(%, Table 2). Notice that recall and the negative dataset is notnecessary for the assessment of agreement.

TABLE 2 Measure of agreement between request and response in fourdomains, % Conversa- tion on Interview Yahoo! Social Customer byJournal- Answers Networks Complaints ists Overall level of 87.2 73.467.4 100 agreement between requests and re- sponse, as deter- mined bySVM TK for RR-CDT Agreement by 61.2 57.3 60.7 70.1 sentiment Agreementby 62.5 60.8 58.4 66.0 logical argumen- tation Agreement by 67.4 67.964.3 82.1 topic as computed by bag-of-words Agreement by 80.2 69.4 66.287.3 topic as computed by generalization of parse trees Agreement by79.4 70.3 64.7 91.6 TK similarity

For example, we estimate as 64.3% the precision of the observation thatthe RR pairs determined by Agreement by topic as computed bybag-of-words approach are valid RR ones in the domain of CustomerComplaints, according to SVM TK for RR-CDT classification.

Agreement by sentiment shows the contribution of proper sentiment matchin RR pair. The sentiment rule includes, in particular, that if thepolarity of RR is the same, response should confirm what request issaying. Conversely, if polarity is opposite, response should attack whatrequest is claiming. Agreement by logical argumentation requires propercommunication discourse where a response disagrees with the claim inrequest.

This data shed a light on the nature of linguistic agreement betweenwhat a proponent is saying and how an opponent is responding. For avalid dialogue discourse, not all agreement features need to be present.However, if most of these features disagree, a given answer should beconsidered invalid, inappropriate and another answer should be selected.Table 2 tells us which features should be used in what degree indialogue support in various domains. The proposed technique cantherefore serve as an automated means of writing quality and customersupport quality assessment.

Chat Bot Applications

A Conversational Agent for Social Promotion (CASP), is an agent that ispresented as a simulated human character which acts on behalf of itshuman host to facilitate and manage her communication for him or her.Galitsky B., Dmitri Ilvovsky, Nina Lebedeva and Daniel Usikov. ImprovingTrust in Automation of Social Promotion. AAAI Spring Symposium on TheIntersection of Robust Intelligence and Trust in Autonomous SystemsStanford Calif. 2014. The CASP relieves its human host from the routine,less important activities on social networks such as sharing news andcommenting on messages, blogs, forums, images and videos of others.Conversational Agent for Social Promotion evolves with possible loss oftrust. The overall performance of CASP with the focus on RR pairagreement, filtering replies mined from the web is evaluated.

On average, people have 200-300 friends or contacts on social networksystems such Facebook and LinkedIn. To maintain active relationshipswith this high number of friends, a few hours per week is required toread what they post and comment on it. In reality, people only maintainrelationship with 10-20 most close friends, family and colleagues, andthe rest of friends are being communicated with very rarely. These notso close friends feel that the social network relationship has beenabandoned. However, maintaining active relationships with all members ofsocial network is beneficial for many aspects of life, from work-relatedto personal. Users of social network are expected to show to theirfriends that they are interested in them, care about them, and thereforereact to events in their lives, responding to messages posted by them.Hence users of social network need to devote a significant amount oftime to maintain relationships on social networks, but frequently do notpossess the time to do it. For close friends and family, users wouldstill socialize manually. For the rest of the network, they would useCASP for social promotion being proposed.

CASP tracks user chats, user postings on blogs and forums, comments onshopping sites, and suggest web documents and their snippets, relevantto a purchase decisions. To do that, it needs to take portions of text,produce a search engine query, run it against a search engine API suchas Bing, and filter out the search results which are determined to beirrelevant to a seed message. The last step is critical for a sensiblefunctionality of CASP, and poor relevance in rhetoric space would leadto lost trust in it. Hence an accurate assessment of RR agreement iscritical to a successful use of CASP.

CASP is presented as a simulated character that acts on behalf of itshuman host to facilitate and manage her communication for her (FIGS.21-22). The agent is designed to relieve its human host from theroutine, less important activities on social networks such as sharingnews and commenting on messages, blogs, forums, images and videos ofothers. Unlike the majority of application domains for simulated humancharacters, its social partners do not necessarily know that theyexchange news, opinions, and updates with an automated agent. Weexperimented with CASP's rhetoric agreement and reasoning about mentalstates of its peers in a number of Facebook accounts. We evaluate itsperformance and accuracy of reasoning about mental states involving thehuman users communicating with it. For a conversational system, usersneed to feel that it properly reacts to their actions, and that what itreplied makes sense. To achieve this in a horizontal domain, one needsto leverage linguistic information to a full degree to be able toexchange messages in a meaningful manner.

CASP inputs a seed (a posting written by a human) and outputs a messageit forms from a content mined on the web and adjusted to be relevant tothe input posting. This relevance is based on the appropriateness interms of content and appropriateness in terms RR agreement, or a mentalstate agreement (for example, it responds by a question to a question,by an answer to a recommendation post seeking more questions, etc.).

FIG. 21-22 illustrate a chat bot commenting on a posting.

We conduct evaluation of how human users lose trust in CASP and his hostin case of both content and mental state relevance failures. Instead ofevaluating rhetoric relevance, which is an intermediate parameter interms of system usability, we assess how users lose trust in CASP whenthey are annoyed by its rhetorically irrelevant and inappropriatepostings.

TABLE 3 Evaluation results for trust losing scenarios A friend A friendshares with encourages Complexity other friends other friends of theseed A friend A friend that the trust to unfriend a Topic of the andposted complains of unfriends the in CASP is friend with seed messageCASP's host CASP host low CASP Travel and 1 sent 6.2 8.5 9.4 12.8outdoor 2 sent 6.0 8.9 9.9 11.4 3 sent 5.9 7.4 10.0 10.8 4 sent 5.2 6.89.4 10.8 Shopping 1 sent 7.2 8.4 9.9 13.1 2 sent 6.8 8.7 9.4 12.4 3 sent6.0 8.4 10.2 11.6 4 sent 5.5 7.8 9.1 11.9 Events and 1 sent 7.3 9.5 10.313.8 entertainment 2 sent 8.1 10.2 10.0 13.9 3 sent 8.4 9.8 10.8 13.7 4sent 8.7 10.0 11.0 13.8 Job-related 1 sent 3.6 4.2 6.1 6.0 2 sent 3.53.9 5.8 6.2 3 sent 3.7 4.0 6.0 6.4 4 sent 3.2 3.9 5.8 6.2 Personal Life1 sent 7.1 7.9 8.4 9.0 2 sent 6.9 7.4 9.0 9.5 3 sent 5.3 7.6 9.4 9.3 4sent 5.9 6.7 7.5 8.9 Average 6.03 7.5 8.87 10.58

In Table 3 we show the results of tolerance of users to the CASPfailures. After a certain number of failures, friends lose trust andcomplain, unfriend, shares negative information about the loss of trustwith others and even encourage other friends to unfriend a friend who isenabled with CASP. The values in the cell indicate the average number ofpostings with failed rhetoric relevance when the respective event oflost trust occurs. These posting of failed relevance occurred within onemonths of this assessment exercise, and we do not obtain the values forthe relative frequency of occurrences of these postings. On average, 100postings were responded for each user (1-4 per seed posting).

One can see that in various domains the scenarios where users lose trustin CASP are different. For less information-critical domains like traveland shopping, tolerance to failed relevance is relatively high.

Conversely, in the domains taken more seriously, like job related, andwith personal flavor, like personal life, users are more sensitive toCASP failures and the loss of trust in its various forms occur faster.

For all domains, tolerance slowly decreases when the complexity ofposting increases. Users' perception is worse for longer texts,irrelevant in terms of content or their expectations, than for shorter,single sentence or phrase postings by CASP.

A Domain of Natural Language Description of Algorithms

The ability to map natural language to a formal query or commandlanguage is critical to developing more user-friendly interfaces to manycomputing systems such as databases. However, relatively little researchhas addressed the problem of learning such semantic parsers from corporaof sentences paired with their formal-language equivalents. Kate,Rohit., Y. W. Wong, and R. Mooney. Learning to transform natural toformal languages. In AAAI, 2005. Furthermore, to the best of ourknowledge no such research was conducted at discourse level. By learningto transform natural language (NL) to a complete formal language, NLinterfaces to complex computing and AI systems can be more easilydeveloped.

More than 40 years ago, Dijkstra, a Dutch computer scientist whoinvented the concept of “structured programming”, wrote: “I suspect thatmachines to be programmed in our native tongues—be it Dutch, English,American, French, German, or Swahili—are as damned difficult to make asthey would be to use”. The visionary was definitely right—thespecialization and the high accuracy of programming languages are whatmade possible the tremendous progress in the computing and computers aswell. Dijkstra compares the invention of programming languages withinvention of mathematical symbolism. In his words “Instead of regardingthe obligation to use formal symbols as a burden, we should regard theconvenience of using them as a privilege: thanks to them, schoolchildren can learn to do what in earlier days only genius couldachieve”. But four decades years later we keep hitting a wall with theamount of code sitting in a typical industry applications—tens andhundreds of millions lines of code—a nightmare to support and develop.The idiom “The code itself is the best description” became kind of a badjoke.

Natural language descriptions of programs is an area where text rhetoricis peculiar and agreement between statements is essential. We will lookat the common rhetoric representation and also domain-specificrepresentation which maps algorithm description into software code.

FIG. 23 illustrates a discourse tree for algorithm text in accordancewith an aspect. We have the following text and its DT (FIG. 23):

1) Find a random pixel p1.

2) Find a convex area a_off this pixel p1 belongs so that all pixels areless than 128.

3) Verify that the border of the selected area has all pixels above 128.

4) If the above verification succeeds, stop with positive result.Otherwise, add all pixels which are below 128 to the a_off.

5) Check that the size of a_off is below the threshold. Then go to 2.Otherwise, stop with negative result.

We now show how to convert a particular sentence into logic form andthen to software code representation. Certain rhetoric relations help tocombine statements obtained as a result of translation of individualsentences.

Verify that the border of the selected area has all pixels above 128.

FIG. 24 illustrates annotated sentences in accordance with an aspect.See FIG. 24 for annotated deconstructions of the pseudocode, 1-1 through1-3.

Converting all constants into variables, we attempt to minimize thenumber of free variables, and not over-constrain the expression at thesame time. Coupled (linked by the edge) arrows show that the sameconstant values (pixel) are mapped into equal variables (Pixel),following the conventions of logic programming. To achieve this, we add(unary) predicates which need to constrain free variables.

1-4) Adding predicates which constrain free variables

epistemic_action(verify) & border(Area) & border(Pixel) & above(Pixel,128) & area(Area)

Now we need to build an explicit expression for quantification all. Inthis particular case it will not be in use, since we use a loopstructure anyway

FIG. 25 illustrates annotated sentences in accordance with an aspect.See FIG. 25 for annotated deconstructions of the pseudocode, 1-5 through2-3.

Finally, we have

2-3) Resultant code fragment

while (!(Pixel.next( )==null)) { if !(border.belong(Pixel) &&Pixel.above(128)){      bOn=false;      break;      } } Return bOn;Related Work

Although discourse analysis has a limited number of applications inquestion answering and summarization and generation of text, we have notfound applications of automatically constructed discourse trees. Weenumerate research related to applications of discourse analysis to twoareas: dialogue management and dialogue games. These areas havepotential of being applied to the same problems the current proposal isintended for. Both of these proposals have a series of logic-basedapproaches as well as analytical and machine learning based ones.

Managing Dialogues and Question Answering

If a question and answer are logically connected, their rhetoricstructure agreement becomes less important.

De Boni proposed a method of determining the appropriateness of ananswer to a question through a proof of logical relevance rather than alogical proof of truth. See De Boni, Marco, Using logical relevance forquestion answering, Journal of Applied Logic, Volume 5, Issue 1, March2007, Pages 92-103. We define logical relevance as the idea that answersshould not be considered as absolutely true or false in relation to aquestion, but should be considered true more flexibly in a sliding scaleof aptness. Then it becomes possible to reason rigorously about theappropriateness of an answer even in cases where the sources of answersare incomplete or inconsistent or contain errors. The authors show howlogical relevance can be implemented through the use of measuredsimplification, a form of constraint relaxation, in order to seek alogical proof than an answer is in fact an answer to a particularquestion.

Our model of CDT attempts to combine general rhetoric and speech actinformation in a single structure. While speech acts provide a usefulcharacterization of one kind of pragmatic force, more recent work,especially in building dialogue systems, has significantly expanded thiscore notion, modeling more kinds of conversational functions that anutterance can play. The resulting enriched acts are called dialogueacts. See Jurafsky, Daniel, & Martin, James H. 2000. Speech and LanguageProcessing: An Introduction to Natural Language Processing,Computational Linguistics, and Speech Recognition. Upper Saddle River,N.J.: Prentice Hall. In their multi-level approach to conversation actsTraum and Hinkelman distinguish four levels of dialogue acts necessaryto assure both coherence and content of conversation. See Traum, DavidR. and James F. Allen. 1994. Discourse obligations in dialogueprocessing. In Proceedings of the 32nd annual meeting on Association forComputational Linguistics (ACL '94). Association for ComputationalLinguistics, Stroudsburg, Pa., USA, 1-8. The four levels of conversationacts are: turn-taking acts, grounding acts, core speech acts, andargumentation acts.

Research on the logical and philosophical foundations of Q/A has beenconducted over a few decades, having focused on limited domains andsystems of rather small size and been found to be of limited use inindustrial environments. The ideas of logical proof of “being an answerto” developed in linguistics and mathematical logic have been shown tohave a limited applicability in actual systems. Most current appliedresearch, which aims to produce working general-purpose (“open-domain”)systems, is based on a relatively simple architecture, combiningInformation Extraction and Retrieval, as was demonstrated by the systemspresented at the standard evaluation framework given by the TextRetrieval Conference (TREC) Q/A track.

(Sperber and Wilson 1986) judged answer relevance depending on theamount of effort needed to “prove” that a particular answer is relevantto a question. This rule can be formulated via rhetoric terms asRelevance Measure: the less hypothetical rhetoric relations are requiredto prove an answer matches the question, the more relevant that answeris. The effort required could be measured in terms of amount of priorknowledge needed, inferences from the text or assumptions. In order toprovide a more manageable measure we propose to simplify the problem byfocusing on ways in which constraints, or rhetoric relations, may beremoved from how the question is formulated. In other words, we measurehow the question may be simplified in order to prove an answer.Resultant rule is formulated as follows: The relevance of an answer isdetermined by how many rhetoric constraints must be removed from thequestion for the answer to be proven; the less rhetoric constraints mustbe removed, the more relevant the answer is.

There is a very limited corpus of research on how discovering rhetoricrelations might help in Q/A. Kontos introduced the system which allowedan exploitation of rhetoric relations between a “basic” text thatproposes a model of a biomedical system and parts of the abstracts ofpapers that present experimental findings supporting this model. SeeKontos, John, Joanna Malagardi, John Peros (2016) Question Answering andRhetoric Analysis of Biomedical Texts in the AROMA System. UnpublishedManuscript.

Adjacency pairs are defined as pairs of utterances that are adjacent,produced by different speakers, ordered as first part and second part,and typed—a particular type of first part requires a particular type ofsecond part. Some of these constraints could be dropped to cover morecases of dependencies between utterances. See Popescu-Belis, Andrei.Dialogue Acts: One or More Dimensions? Tech Report ISSCO Working papern. 62. 2005.

Adjacency pairs are relational by nature, but they could be reduced tolabels (‘first part’, ‘second part’, ‘none’), possibly augmented with apointer towards the other member of the pair. Frequently encounteredobserved kinds of adjacency pairs include the following ones:request/offer/invite→accept/refuse; assess→agree/disagree;blame→denial/admission; question→answer; apology→downplay;thank→welcome; greeting→greeting. See Levinson, Stephen C. 2000.Presumptive Meanings: The Theory of Generalized ConversationalImplicature. Cambridge, Mass.: The MIT Press.

Rhetoric relations, similarly to adjacency pairs, are a relationalconcept, concerning relations between utterances, not utterances inisolation. It is however possible, given that an utterance is asatellite with respect to a nucleus in only one relation, to assign tothe utterance the label of the relation. This poses strong demand for adeep analysis of dialogue structure. The number of rhetoric relations inRST ranges from the ‘dominates’ and ‘satisfaction-precedes’ classes usedby (Grosz and Sidner 1986) to more than a hundred types. Coherencerelations are an alternative way to express rhetoric structure in text.See Scholman, Merel, Jacqueline Evers-Vermeul, Ted Sanders. Categoriesof coherence relations in discourse annotation. Dialogue & Discourse,Vol 7, No 2 (2016)

There are many classes of NLP applications that are expected to leverageinformational structure of text. DT can be very useful is textsummarization. Knowledge of salience of text segments, based onnucleus-satellite relations proposed by Sparck-Jones 1995 and thestructure of relation between segments should be taken into account toform exact and coherent summaries. See Sparck Jones, K. Summarising:analytic framework, key component, experimental method’, in SummarisingText for Intelligent Communication, (Ed. B. Endres-Niggemeyer, J. Hobbsand K. Sparck Jones), Dagstuhl Seminar Report 79 (1995). One cangenerate the most informative summary by combining the most importantsegments of elaboration relations starting at the root node. DTs havebeen used for multi-document summaries. See Radev, Dragomir R., HongyanJing, and Malgorzata Budzikowska. 2000. Centroid-based summarization ofmultiple documents: sentence extraction, utility-based evaluation, anduser studies. In Proceedings of the 2000 NAACL-ANLP Workshop onAutomatic summarization—Volume 4

In the natural language generation problem, whose main difficulty iscoherence, informational structure of text can be relied upon toorganize the extracted fragments of text in a coherent way. A way tomeasure text coherence can be used in automated evaluation of essays.Since a DT can capture text coherence, then yielding discoursestructures of essays can be used to assess the writing style and qualityof essays. Burstein described a semi-automatic way for essay assessmentthat evaluated text coherence. See Burstein, Jill C., LisaBraden-Harder, Martin S. Chodorow, Bruce A. Kaplan, Karen Kukich, ChiLu, Donald A. Rock and Susanne Wolff (2002).

The neural network language model proposed in (engio 2003 uses theconcatenation of several preceding word vectors to form the input of aneural network, and tries to predict the next word. See Bengio, Yoshua,Réjean Ducharme, Pascal Vincent, and Christian Janvin. 2003. A neuralprobabilistic language model. J. Mach. Learn. Res. 3 (March 2003),1137-1155. The outcome is that after the model is trained, the wordvectors are mapped into a vector space such that DistributedRepresentations of Sentences and Documents semantically similar wordshave similar vector representations. This kind of model can potentiallyoperate on discourse relations, but it is hard to supply as richlinguistic information as we do for tree kernel learning. There is acorpus of research that extends word2vec models to go beyond word levelto achieve phrase-level or sentence-level representations. For instance,a simple approach is using a weighted average of all the words in thedocument, (weighted averaging of word vectors), losing the word ordersimilar to how bag-of-words approaches do. A more sophisticated approachis combining the word vectors in an order given by a parse tree of asentence, using matrix-vector operations. See R. Socher, C. D. Manning,and A. Y. Ng. 2010. Learning continuous phrase representations andsyntactic parsing with recursive neural networks. In Proceedings of theNIPS-2010 Deep Learning and Unsupervised Feature Learning Workshop.Using a parse tree to combine word vectors, has been shown to work foronly sentences because it relies on parsing.

Many early approaches to policy learning for dialogue systems used smallstate spaces and action sets, and concentrated on only limited policylearning experiments (for example, type of confirmation, or type ofinitiative). The Communicator dataset (Walker et al 2001) is the largestavailable corpus of human-machine dialogues, and has been furtherannotated with dialogue contexts. This corpus has been extensively usedfor training and testing dialogue managers, however it is restricted toinformation requesting dialogues in the air travel domain for a limitednumber of attributes such as destination city. At the same time, in thecurrent work we relied on the extensive corpus of request-response pairsof various natures.

Reichman 1985 gives a formal description and an ATN (AugmentedTransition Network) model of conversational moves, with reference toconventional methods for recognizing the speech act of an utterance. Theauthor uses the analysis of linguistic markers similar to what is nowused for rhetoric parsing such as pre-verbal ‘please’, modalauxiliaries, prosody, reference, clue phrases (such as ‘Yes, but . . . ’(sub-argument concession and counter argument), ‘Yes, and . . . ’(argument agreement and further support), ‘No’ and ‘Yes’(disagreement/agreement), ‘Because . . . ’ (support), etc.) and otherillocutionary indicators. See Reichman, R. 1985. Getting computers totalk like you and me: discourse context, focus and semantics (an ATNmodel). Cambridge, Mass. London: MIT Press.

Given a DT for a text as a candidate answer to a compound query,proposed a rule system for valid and invalid occurrence of the querykeywords in this DT. See Galisky 2015. To be a valid answer to a query,its keywords need to occur in a chain of elementary discourse units ofthis answer so that these units are fully ordered and connected bynucleus—satellite relations. An answer might be invalid if the queries'keywords occur in the answer's satellite discourse units only.

Dialog Games

In an arbitrary conversation, a question is typically followed by ananswer, or some explicit statement of an inability or refusal to answer.There is the following model of the intentional space of a conversation.From the yielding of a question by Agent B, Agent A recognizes Agent B'sgoal to find out the answer, and it adopts a goal to tell B the answerin order to be co-operative. A then plans to achieve the goal, therebygenerating the answer. This provides an elegant account in the simplecase, but requires a strong assumption of co-operativeness. Agent A mustadopt agent B's goals as her own. As a result, it does not explain why Asays anything when she does not know the answer or when she is not readyto accept B's goals.

Litman and Allen introduced an intentional analysis at the discourselevel in addition to the domain level, and assumed a set of conventionalmulti-agent actions at the discourse level. See Litman, D. L. and Allen,J. F. 1987. A plan recognition model for subdialogues in conversation,Cognitive Science, 11: 163-2. Others have tried to account for this kindof behavior using social intentional constructs such as Jointintentions. See Cohen P. R. & Levesque, H. J. 1990. Intention is choicewith commitment, Artificial Intelligence, 42: 213-261. See also Grosz,Barbara J., & Sidner, Candace L. 1986. Attentions, Intentions and theStructure of Discourse. Computational Linguistics, 12(3), 175-204. Whilethese accounts do help explain some discourse phenomena moresatisfactorily, they still require a strong degree of cooperativity toaccount for dialogue coherence, and do not provide easy explanations ofwhy an agent might act in cases that do not support high-level mutualgoals.

Let us imagine a stranger approaching a person and asking, “Do you havespare coins?” It is unlikely that there is a joint intention or sharedplan, as they have never met before. From a purely strategic point ofview, the agent may have no interest in whether the stranger's goals aremet. Yet, typically agents will still respond in such situations. Hencean account of Q/A must go beyond recognition of speaker intentions.Questions do more than just provide evidence of a speaker's goals, andsomething more than adoption of the goals of an interlocutor is involvedin formulating a response to a question.

Mann proposed a library of discourse level actions, sometimes calleddialogue games, which encode common communicative interactions. SeeMann, William and Sandra Thompson. 1988. Rhetorical structure theory:Towards a functional theory of text organization. Text-InterdisciplinaryJournal for the Study of Discourse, 8(3):243-281. To be co-operative, anagent must always be participating in one of these games. So if aquestion is asked, only a fixed number of activities, namely thoseintroduced by a question, are co-operative responses. Games provide abetter explanation of coherence, but still require the agents torecognize each other's intentions to perform the dialogue game. As aresult, this work can be viewed as a special case of the intentionalview. Because of this separation, they do not have to assumeco-operation on the tasks each agent is performing, but still requirerecognition of intention and co-operation at the conversational level.It is left unexplained what goals motivate conversational co-operation.

Coulthard and Brazil suggested that responses can play a dual role ofboth response and new initiation: Initiation{circumflex over( )}(Re-Initiation){circumflex over ( )}Response A(Follow-up). SeeCoulthard, R. M. and Brazil D. 1979. Exchange structure: Discourseanalysis monographs no. 5. Birmingham: The University of Birmingham,English Language Research. Exchanges can consist of two to fourutterances. Also, follow-up itself could be followed up. Opening movesindicate the start of the exchange sometimes, which do not restrict thetype of the next move. Finally, closing moves sometimes occur which arenot necessarily a follow-up. When these observations are added to theirformula one ends up with:

(Open){circumflex over ( )}Initiation{circumflex over( )}(Re-Initiation){circumflex over ( )}Response{circumflex over( )}(Feedback) A(Follow-up){circumflex over ( )}(Close)

This now can deal with anything from two to seven more exchanges.

FIG. 26 illustrates discourse acts of a dialogue in accordance with anaspect. Tsui (1994) characterizes the discourse acts according to athree-part transaction. Her systems of choice for Initiating, Respondingand Follow-up are shown in FIG. 26 on the top, middle and bottomcorrespondingly.

FIG. 27 illustrates discourse acts of a dialogue in accordance with anaspect.

The classification problem of valid vs invalid RR pairs is alsoapplicable to the task of complete dialogue generation beyond questionanswering and automated dialogue support. Popescu presented alogic-based rhetorical structuring component of a natural languagegenerator for human-computer dialogue. See Popescu, Vladimir, JeanCaelen, Corneliu Burileanu. Logic-Based Rhetorical Structuring forNatural Language Generation in Human-Computer Dialogue. Lecture Notes inComputer Science Volume 4629, pp 309-317, 2007. The pragmatic andcontextual aspects are taken into account communicating with a taskcontroller providing domain and application-dependent information,structured in fully formalized task ontology. In order to achieve thegoal of computational feasibility and generality, discourse ontology hasbeen built and a number of axioms introducing constraints for rhetoricrelations have been proposed.

For example, the axiom specifying the semantics of topic(α) is givenbelow:

topic(α)  ::= ExhaustiveDecomposition(i, j ; vi , ωj ) &memberOf(vi , K (α)) & memberOf(ωj,Ω)(∃k : equals(vk,ωj) &memberOf(vk,K(α))).where K(α) the clause logically expressing the semantics of theutterance a.

The notion of topic of an utterance is defined here in terms of sets ofobjects in the domain ontology, referred to in a determined manner inthe utterance. Hence, the topic relations between utterances arecomputed using the task/domain ontology, handled by the task controller.

As an instance of such rule one can consider

topic(β) ::= ExhaustiveDecomposition(book, read, good time(’14h’), goodtime(’monday’), t+); −good time(θ) ::= ∃γ,π : ¬Disjoint(topic(γ),topic(π)) & smaller(tα,tπ) & ((SubclassOf(θ, Δtα) □ equals(θ,Δtα)) & π :equals(Δtπ,θ);where t+ is “future and ‘new’”.Rhetoric Relations and Argumentation

Frequently, the main means of linking questions and answers is logicalargumentation. There is an obvious connection between RST andargumentation relations which tried to learn in this study. There arefour types of relations: the directed relations support, attack, detail,and the undirected sequence relation. The support and attack relationsare argumentative relations, which are known from related work. SeePeldszus, A. and Stede, M. 2013. From Argument Diagrams to ArgumentationMining in Texts: A Survey. Int. J of Cognitive Informatics and NaturalIntelligence 7(1), 1-31). The latter two correspond to discourserelations used in RST. The argumentation sequence relation correspondsto “Sequence” in RST, the argumentation detail relation roughlycorresponds to “Background” and “Elaboration”.

Argumentation detail relation is important because many cases inscientific publications, where some background information (for examplethe definition of a term) is important for understanding the overallargumentation. A support relation between an argument component Resp andanother argument component Req indicates that Resp supports (reasons,proves) Req. Similarly, an attack relation between Resp and Req isannotated if Resp attacks (restricts, contradicts) Req. The detailrelation is used, if Resp is a detail of Req and gives more informationor defines something stated in Req without argumentative reasoning.Finally, we link two argument components (within Req or Resp) with thesequence relation, if the components belong together and only make sensein combination, i.e., they form a multi-sentence argument component.

We observed that using SVM TK one can differentiate between a broadrange of text styles (Galitsky 2015), including ones withoutargumentation and ones with various forms of argumentation. Each textstyle and genre has its inherent rhetoric structure which is leveragedand automatically learned. Since the correlation between text style andtext vocabulary is rather low, traditional classification approacheswhich only take into account keyword statistics information could lackthe accuracy in the complex cases. We also performed text classificationinto rather abstract classes such as the belonging to language-objectand metalanguage in literature domain and style-based documentclassification into proprietary design documents. See Galitsky, B,Ilvovsky, D. and Kuznetsov S O. Rhetoric Map of an Answer to CompoundQueries Knowledge Trail Inc. ACL 2015, 681-686. Evaluation of textintegrity in the domain of valid vs invalid customer complains (thosewith argumentation flow, non-cohesive, indicating a bad mood of acomplainant) shows the stronger contribution of rhetoric structureinformation in comparison with the sentiment profile information.Discourse structures obtained by RST parser are sufficient to conductthe text integrity assessment, whereas sentiment profile-based approachshows much weaker results and also does not complement strongly therhetoric structure ones.

An extensive corpus of studies has been devoted to RST parsers, but theresearch on how to leverage RST parsing results for practical NLPproblems is limited to content generation, summarization and search(Jansen et al 2014). DTs obtained by these parsers cannot be useddirectly in a rule-based manner to filter or construct texts. Therefore,learning is required to leverage implicit properties of DTs. This studyis a pioneering one, to the best of our knowledge, that employsdiscourse trees and their extensions for general and open-domainquestion answering, chatbots, dialogue management and text construction.

Dialogue chatbot systems need to be capable of understanding andmatching user communicative intentions, reason with these intentions,build their own respective communication intentions and populate theseintentions with actual language to be communicated to the user.Discourse trees on their own do not provide representation for thesecommunicative intents. In this study we introduced the communicativediscourse trees, built upon the traditional discourse trees, which canbe massively produced nowadays on one hand and constitute a descriptiveutterance-level model of a dialogue on the other hand. Handlingdialogues via machine learning of communicative discourse trees allowedus to model a wide array of dialogue types of collaboration modes andinteraction types (planning, execution, and interleaved planning andexecution).

Statistical computational learning approaches offer several keypotential advantages over the manual rule-based hand-coding approach todialogue systems development:

-   -   data-driven development cycle;    -   provably optimal action policies;    -   a more accurate model for the selection of responses;    -   possibilities for generalization to unseen states;    -   reduced development and deployment costs for industry.

Comparing inductive learning results with the kernel-based statisticallearning, relying on the same information allowed us to perform moreconcise feature engineering than either approach would do.

An extensive corpus of literature on RST parsers does not address theissue of how the resultant DT will be employed in practical NLP systems.RST parsers are mostly evaluated with respect to agreement with the testset annotated by humans rather than its expressiveness of the featuresof interest. In this work we focus on interpretation of DT and exploredways to represent them in a form indicative of an agreement ordisagreement rather than neutral enumeration of facts.

To provide a measure of agreement for how a given message in a dialogueis followed by a next message, we used CDTs, which now include labelsfor communicative actions in the form of substituted VerbNet frames. Weinvestigated the discourse features that are indicative of correct vsincorrect request-response and question-answer pairs. We used twolearning frameworks to recognize correct pairs: deterministic,nearest-neighbor learning of CDTs as graphs, and a tree kernel learningof CDTs, where a feature space of all CDT sub-trees is subject to SVMlearning.

The positive training set was constructed from the correct pairsobtained from Yahoo Answers, social network, corporate conversationsincluding Enron emails, customer complaints and interviews byjournalists. The corresponding negative training set was created byattaching responses for different, random requests and questions thatincluded relevant keywords so that relevance similarity between requestsand responses are high. The evaluation showed that it is possible torecognize valid pairs in 68-79% of cases in the domains of weakrequest-response agreement and 80-82% of cases in the domains of strongagreement. These accuracies are essential to support automatedconversations. These accuracies are comparable with the benchmark taskof classification of discourse trees themselves as valid or invalid, andalso with factoid question-answering systems.

We believe this study is the first one that leverages automaticallybuilt discourse trees for question answering support. Previous studiesused specific, customer discourse models and features which are hard tosystematically collect, learn with explainability, reverse engineer andcompare with each other. We conclude that learning rhetoric structuresin the form of CDTs are key source of data to support answering complexquestions, chatbots and dialogue management.

FIG. 28 depicts a simplified diagram of a distributed system 2800 forimplementing one of the aspects. In the illustrated aspect, distributedsystem 2800 includes one or more client computing devices 2802, 2804,2806, and 2808, which are configured to execute and operate a clientapplication such as a web browser, proprietary client (e.g., OracleForms), or the like over one or more network(s) 2810. Server 2812 may becommunicatively coupled with remote client computing devices 2802, 2804,2806, and 2808 via network 2810.

In various aspects, server 812 may be adapted to run one or moreservices or software applications provided by one or more of thecomponents of the system. The services or software applications caninclude nonvirtual and virtual environments. Virtual environments caninclude those used for virtual events, tradeshows, simulators,classrooms, shopping exchanges, and enterprises, whether two- orthree-dimensional (3D) representations, page-based logical environments,or otherwise. In some aspects, these services may be offered asweb-based or cloud services or under a Software as a Service (SaaS)model to the users of client computing devices 2802, 2804, 2806, and/or2808. Users operating client computing devices 2802, 2804, 2806, and/or2808 may in turn utilize one or more client applications to interactwith server 2812 to utilize the services provided by these components.

In the configuration depicted in the figure, the software components2818, 2820 and 2822 of system 2800 are shown as being implemented onserver 812. In other aspects, one or more of the components of system2800 and/or the services provided by these components may also beimplemented by one or more of the client computing devices 2802, 2804,2806, and/or 2808. Users operating the client computing devices may thenutilize one or more client applications to use the services provided bythese components. These components may be implemented in hardware,firmware, software, or combinations thereof. It should be appreciatedthat various different system configurations are possible, which may bedifferent from distributed system 2800. The aspect shown in the figureis thus one example of a distributed system for implementing an aspectsystem and is not intended to be limiting.

Client computing devices 2802, 2804, 2806, and/or 2808 may be portablehandheld devices (e.g., an iPhone®, cellular telephone, an iPad®,computing tablet, a personal digital assistant (PDA)) or wearabledevices (e.g., a Google Glass® head mounted display), running softwaresuch as Microsoft Windows Mobile®, and/or a variety of mobile operatingsystems such as iOS, Windows Phone, Android, BlackBerry 10, Palm OS, andthe like, and being Internet, e-mail, short message service (SMS),Blackberry®, or other communication protocol enabled. The clientcomputing devices can be general purpose personal computers including,by way of example, personal computers and/or laptop computers runningvarious versions of Microsoft Windows®, Apple Macintosh®, and/or Linuxoperating systems. The client computing devices can be workstationcomputers running any of a variety of commercially-available UNIX® orUNIX-like operating systems, including without limitation the variety ofGNU/Linux operating systems, such as for example, Google Chrome OS.Alternatively, or in addition, client computing devices 2802, 2804,2806, and 2808 may be any other electronic device, such as a thin-clientcomputer, an Internet-enabled gaming system (e.g., a Microsoft Xboxgaming console with or without a Kinect® gesture input device), and/or apersonal messaging device, capable of communicating over network(s)2810.

Although exemplary distributed system 2800 is shown with four clientcomputing devices, any number of client computing devices may besupported. Other devices, such as devices with sensors, etc., mayinteract with server 2812.

Network(s) 2810 in distributed system 2800 may be any type of networkfamiliar to those skilled in the art that can support datacommunications using any of a variety of commercially-availableprotocols, including without limitation TCP/IP (transmission controlprotocol/Internet protocol), SNA (systems network architecture), IPX(Internet packet exchange), AppleTalk, and the like. Merely by way ofexample, network(s) 2810 can be a local area network (LAN), such as onebased on Ethernet, Token-Ring and/or the like. Network(s) 2810 can be awide-area network and the Internet. It can include a virtual network,including without limitation a virtual private network (VPN), anintranet, an extranet, a public switched telephone network (PSTN), aninfra-red network, a wireless network (e.g., a network operating underany of the Institute of Electrical and Electronics (IEEE) 802.28 suiteof protocols, Bluetooth®, and/or any other wireless protocol); and/orany combination of these and/or other networks.

Server 2812 may be composed of one or more general purpose computers,specialized server computers (including, by way of example, PC (personalcomputer) servers, UNIX® servers, mid-range servers, mainframecomputers, rack-mounted servers, etc.), server farms, server clusters,or any other appropriate arrangement and/or combination. Server 2812 caninclude one or more virtual machines running virtual operating systems,or other computing architectures involving virtualization. One or moreflexible pools of logical storage devices can be virtualized to maintainvirtual storage devices for the server. Virtual networks can becontrolled by server 2812 using software defined networking. In variousaspects, server 2812 may be adapted to run one or more services orsoftware applications described in the foregoing disclosure. Forexample, server 2812 may correspond to a server for performingprocessing described above according to an aspect of the presentdisclosure.

Server 2812 may run an operating system including any of those discussedabove, as well as any commercially available server operating system.Server 2812 may also run any of a variety of additional serverapplications and/or mid-tier applications, including HTTP (hypertexttransport protocol) servers, FTP (file transfer protocol) servers, CGI(common gateway interface) servers, JAVA® servers, database servers, andthe like. Exemplary database servers include without limitation thosecommercially available from Oracle, Microsoft, Sybase, IBM(International Business Machines), and the like.

In some implementations, server 2812 may include one or moreapplications to analyze and consolidate data feeds and/or event updatesreceived from users of client computing devices 802, 804, 806, and 808.As an example, data feeds and/or event updates may include, but are notlimited to, Twitter® feeds, Facebook® updates or real-time updatesreceived from one or more third party information sources and continuousdata streams, which may include real-time events related to sensor dataapplications, financial tickers, network performance measuring tools(e.g., network monitoring and traffic management applications),clickstream analysis tools, automobile traffic monitoring, and the like.Server 2812 may also include one or more applications to display thedata feeds and/or real-time events via one or more display devices ofclient computing devices 2802, 2804, 2806, and 2808.

Distributed system 2800 may also include one or more databases 2814 and2816. Databases 2814 and 2816 may reside in a variety of locations. Byway of example, one or more of databases 2814 and 2816 may reside on anon-transitory storage medium local to (and/or resident in) server 2812.Alternatively, databases 2814 and 2816 may be remote from server 2812and in communication with server 2812 via a network-based or dedicatedconnection. In one set of aspects, databases 2814 and 2816 may reside ina storage-area network (SAN). Similarly, any necessary files forperforming the functions attributed to server 2812 may be stored locallyon server 2812 and/or remotely, as appropriate. In one set of aspects,databases 2814 and 2816 may include relational databases, such asdatabases provided by Oracle, that are adapted to store, update, andretrieve data in response to SQL-formatted commands.

FIG. 29 is a simplified block diagram of one or more components of asystem environment 2900 by which services provided by one or morecomponents of an aspect system may be offered as cloud services, inaccordance with an aspect of the present disclosure. In the illustratedaspect, system environment 2900 includes one or more client computingdevices 2904, 2906, and 2908 that may be used by users to interact witha cloud infrastructure system 2902 that provides cloud services. Theclient computing devices may be configured to operate a clientapplication such as a web browser, a proprietary client application(e.g., Oracle Forms), or some other application, which may be used by auser of the client computing device to interact with cloudinfrastructure system 2902 to use services provided by cloudinfrastructure system 2902.

It should be appreciated that cloud infrastructure system 2902 depictedin the figure may have other components than those depicted. Further,the aspect shown in the figure is only one example of a cloudinfrastructure system that may incorporate an aspect of the invention.In some other aspects, cloud infrastructure system 2902 may have more orfewer components than shown in the figure, may combine two or morecomponents, or may have a different configuration or arrangement ofcomponents.

Client computing devices 2904, 2906, and 2908 may be devices similar tothose described above for 2802, 2804, 2806, and 2808.

Although exemplary system environment 2900 is shown with three clientcomputing devices, any number of client computing devices may besupported. Other devices such as devices with sensors, etc. may interactwith cloud infrastructure system 2902.

Network(s) 2910 may facilitate communications and exchange of databetween clients 2904, 2906, and 2908 and cloud infrastructure system2902. Each network may be any type of network familiar to those skilledin the art that can support data communications using any of a varietyof commercially-available protocols, including those described above fornetwork(s) 2810.

Cloud infrastructure system 2902 may comprise one or more computersand/or servers that may include those described above for server 2829.

In certain aspects, services provided by the cloud infrastructure systemmay include a host of services that are made available to users of thecloud infrastructure system on demand, such as online data storage andbackup solutions, Web-based e-mail services, hosted office suites anddocument collaboration services, database processing, managed technicalsupport services, and the like. Services provided by the cloudinfrastructure system can dynamically scale to meet the needs of itsusers. A specific instantiation of a service provided by cloudinfrastructure system is referred to herein as a “service instance.” Ingeneral, any service made available to a user via a communicationnetwork, such as the Internet, from a cloud service provider's system isreferred to as a “cloud service.” Typically, in a public cloudenvironment, servers and systems that make up the cloud serviceprovider's system are different from the customer's own on-premisesservers and systems. For example, a cloud service provider's system mayhost an application, and a user may, via a communication network such asthe Internet, on demand, order and use the application.

In some examples, a service in a computer network cloud infrastructuremay include protected computer network access to storage, a hosteddatabase, a hosted web server, a software application, or other serviceprovided by a cloud vendor to a user, or as otherwise known in the art.For example, a service can include password-protected access to remotestorage on the cloud through the Internet. As another example, a servicecan include a web service-based hosted relational database and ascript-language middleware engine for private use by a networkeddeveloper. As another example, a service can include access to an emailsoftware application hosted on a cloud vendor's web site.

In certain aspects, cloud infrastructure system 2902 may include a suiteof applications, middleware, and database service offerings that aredelivered to a customer in a self-service, subscription-based,elastically scalable, reliable, highly available, and secure manner. Anexample of such a cloud infrastructure system is the Oracle Public Cloudprovided by the present assignee.

Large volumes of data, sometimes referred to as big data, can be hostedand/or manipulated by the infrastructure system on many levels and atdifferent scales. Such data can include data sets that are so large andcomplex that it can be difficult to process using typical databasemanagement tools or traditional data processing applications. Forexample, terabytes of data may be difficult to store, retrieve, andprocess using personal computers or their rack-based counterparts. Suchsizes of data can be difficult to work with using most currentrelational database management systems and desktop statistics andvisualization packages. They can require massively parallel processingsoftware running thousands of server computers, beyond the structure ofcommonly used software tools, to capture, curate, manage, and processthe data within a tolerable elapsed time.

Extremely large data sets can be stored and manipulated by analysts andresearchers to visualize large amounts of data, detect trends, and/orotherwise interact with the data. Tens, hundreds, or thousands ofprocessors linked in parallel can act upon such data in order to presentit or simulate external forces on the data or what it represents. Thesedata sets can involve structured data, such as that organized in adatabase or otherwise according to a structured model, and/orunstructured data (e.g., emails, images, data blobs (binary largeobjects), web pages, complex event processing). By leveraging an abilityof an aspect to relatively quickly focus more (or fewer) computingresources upon an objective, the cloud infrastructure system may bebetter available to carry out tasks on large data sets based on demandfrom a business, government agency, research organization, privateindividual, group of like-minded individuals or organizations, or otherentity.

In various aspects, cloud infrastructure system 2902 may be adapted toautomatically provision, manage and track a customer's subscription toservices offered by cloud infrastructure system 2902. Cloudinfrastructure system 2902 may provide the cloud services via differentdeployment models. For example, services may be provided under a publiccloud model in which cloud infrastructure system 2902 is owned by anorganization selling cloud services (e.g., owned by Oracle) and theservices are made available to the general public or different industryenterprises. As another example, services may be provided under aprivate cloud model in which cloud infrastructure system 2902 isoperated solely for a single organization and may provide services forone or more entities within the organization. The cloud services mayalso be provided under a community cloud model in which cloudinfrastructure system 2902 and the services provided by cloudinfrastructure system 2902 are shared by several organizations in arelated community. The cloud services may also be provided under ahybrid cloud model, which is a combination of two or more differentmodels.

In some aspects, the services provided by cloud infrastructure system2902 may include one or more services provided under Software as aService (SaaS) category, Platform as a Service (PaaS) category,Infrastructure as a Service (IaaS) category, or other categories ofservices including hybrid services. A customer, via a subscriptionorder, may order one or more services provided by cloud infrastructuresystem 2902. Cloud infrastructure system 2902 then performs processingto provide the services in the customer's subscription order.

In some aspects, the services provided by cloud infrastructure system2902 may include, without limitation, application services, platformservices and infrastructure services. In some examples, applicationservices may be provided by the cloud infrastructure system via a SaaSplatform. The SaaS platform may be configured to provide cloud servicesthat fall under the SaaS category. For example, the SaaS platform mayprovide capabilities to build and deliver a suite of on-demandapplications on an integrated development and deployment platform. TheSaaS platform may manage and control the underlying software andinfrastructure for providing the SaaS services. By utilizing theservices provided by the SaaS platform, customers can utilizeapplications executing on the cloud infrastructure system. Customers canacquire the application services without the need for customers topurchase separate licenses and support. Various different SaaS servicesmay be provided. Examples include, without limitation, services thatprovide solutions for sales performance management, enterpriseintegration, and business flexibility for large organizations.

In some aspects, platform services may be provided by the cloudinfrastructure system via a PaaS platform. The PaaS platform may beconfigured to provide cloud services that fall under the PaaS category.Examples of platform services may include without limitation servicesthat enable organizations (such as Oracle) to consolidate existingapplications on a shared, common architecture, as well as the ability tobuild new applications that leverage the shared services provided by theplatform. The PaaS platform may manage and control the underlyingsoftware and infrastructure for providing the PaaS services. Customerscan acquire the PaaS services provided by the cloud infrastructuresystem without the need for customers to purchase separate licenses andsupport. Examples of platform services include, without limitation,Oracle Java Cloud Service (JCS), Oracle Database Cloud Service (DBCS),and others.

By utilizing the services provided by the PaaS platform, customers canemploy programming languages and tools supported by the cloudinfrastructure system and also control the deployed services. In someaspects, platform services provided by the cloud infrastructure systemmay include database cloud services, middleware cloud services (e.g.,Oracle Fusion Middleware services), and Java cloud services. In oneaspect, database cloud services may support shared service deploymentmodels that enable organizations to pool database resources and offercustomers a Database as a Service in the form of a database cloud.Middleware cloud services may provide a platform for customers todevelop and deploy various business applications, and Java cloudservices may provide a platform for customers to deploy Javaapplications, in the cloud infrastructure system.

Various different infrastructure services may be provided by an IaaSplatform in the cloud infrastructure system. The infrastructure servicesfacilitate the management and control of the underlying computingresources, such as storage, networks, and other fundamental computingresources for customers utilizing services provided by the SaaS platformand the PaaS platform.

In certain aspects, cloud infrastructure system 2902 may also includeinfrastructure resources 2930 for providing the resources used toprovide various services to customers of the cloud infrastructuresystem. In one aspect, infrastructure resources 2930 may includepre-integrated and optimized combinations of hardware, such as servers,storage, and networking resources to execute the services provided bythe PaaS platform and the SaaS platform.

In some aspects, resources in cloud infrastructure system 2902 may beshared by multiple users and dynamically re-allocated per demand.Additionally, resources may be allocated to users in different timezones. For example, cloud infrastructure system 2930 may enable a firstset of users in a first time zone to utilize resources of the cloudinfrastructure system for a specified number of hours and then enablethe re-allocation of the same resources to another set of users locatedin a different time zone, thereby maximizing the utilization ofresources.

In certain aspects, a number of internal shared services 2932 may beprovided that are shared by different components or modules of cloudinfrastructure system 2902 and by the services provided by cloudinfrastructure system 2902. These internal shared services may include,without limitation, a security and identity service, an integrationservice, an enterprise repository service, an enterprise managerservice, a virus scanning and white list service, a high availability,backup and recovery service, service for enabling cloud support, anemail service, a notification service, a file transfer service, and thelike.

In certain aspects, cloud infrastructure system 2902 may providecomprehensive management of cloud services (e.g., SaaS, PaaS, and IaaSservices) in the cloud infrastructure system. In one aspect, cloudmanagement functionality may include capabilities for provisioning,managing and tracking a customer's subscription received by cloudinfrastructure system 2902, and the like.

In one aspect, as depicted in the figure, cloud management functionalitymay be provided by one or more modules, such as an order managementmodule 2920, an order orchestration module 2922, an order provisioningmodule 2924, an order management and monitoring module 2926, and anidentity management module 2928. These modules may include or beprovided using one or more computers and/or servers, which may begeneral purpose computers, specialized server computers, server farms,server clusters, or any other appropriate arrangement and/orcombination.

In exemplary operation 2934, a customer using a client device, such asclient device 2904, 2906 or 2908, may interact with cloud infrastructuresystem 2902 by requesting one or more services provided by cloudinfrastructure system 2902 and placing an order for a subscription forone or more services offered by cloud infrastructure system 2902. Incertain aspects, the customer may access a cloud User Interface (UI),cloud UI 2929, cloud UI 2914 and/or cloud UI 2916 and place asubscription order via these UIs. The order information received bycloud infrastructure system 2902 in response to the customer placing anorder may include information identifying the customer and one or moreservices offered by the cloud infrastructure system 2902 that thecustomer intends to subscribe to.

After an order has been placed by the customer, the order information isreceived via the cloud UIs, 2929, 2914 and/or 2916.

At operation 2936, the order is stored in order database 2918. Orderdatabase 2918 can be one of several databases operated by cloudinfrastructure system 2918 and operated in conjunction with other systemelements.

At operation 2938, the order information is forwarded to an ordermanagement module 2920. In some instances, order management module 2920may be configured to perform billing and accounting functions related tothe order, such as verifying the order, and upon verification, bookingthe order.

At operation 2940, information regarding the order is communicated to anorder orchestration module 2922. Order orchestration module 2922 mayutilize the order information to orchestrate the provisioning ofservices and resources for the order placed by the customer. In someinstances, order orchestration module 2922 may orchestrate theprovisioning of resources to support the subscribed services using theservices of order provisioning module 2924.

In certain aspects, order orchestration module 2922 enables themanagement of business processes associated with each order and appliesbusiness logic to determine whether an order should proceed toprovisioning. At operation 2942, upon receiving an order for a newsubscription, order orchestration module 2922 sends a request to orderprovisioning module 2924 to allocate resources and configure thoseresources needed to fulfill the subscription order. Order provisioningmodule 2924 enables the allocation of resources for the services orderedby the customer. Order provisioning module 2924 provides a level ofabstraction between the cloud services provided by cloud infrastructuresystem 2900 and the physical implementation layer that is used toprovision the resources for providing the requested services. Orderorchestration module 2922 may thus be isolated from implementationdetails, such as whether or not services and resources are actuallyprovisioned on the fly or pre-provisioned and only allocated/assignedupon request.

At operation 2944, once the services and resources are provisioned, anotification of the provided service may be sent to customers on clientdevices 2904, 2906 and/or 2908 by order provisioning module 2924 ofcloud infrastructure system 2902.

At operation 2946, the customer's subscription order may be managed andtracked by an order management and monitoring module 2926. In someinstances, order management and monitoring module 2926 may be configuredto collect usage statistics for the services in the subscription order,such as the amount of storage used, the amount data transferred, thenumber of users, and the amount of system up time and system down time.

In certain aspects, cloud infrastructure system 2900 may include anidentity management module 2928. Identity management module 2928 may beconfigured to provide identity services, such as access management andauthorization services in cloud infrastructure system 2900. In someaspects, identity management module 2928 may control information aboutcustomers who wish to utilize the services provided by cloudinfrastructure system 2902. Such information can include informationthat authenticates the identities of such customers and information thatdescribes which actions those customers are authorized to performrelative to various system resources (e.g., files, directories,applications, communication ports, memory segments, etc.) Identitymanagement module 2928 may also include the management of descriptiveinformation about each customer and about how and by whom thatdescriptive information can be accessed and modified.

FIG. 30 illustrates an exemplary computer system 3000, in which variousaspects of the present invention may be implemented. The system 3000 maybe used to implement any of the computer systems described above. Asshown in the figure, computer system 3000 includes a processing unit3004 that communicates with a number of peripheral subsystems via a bussubsystem 3002. These peripheral subsystems may include a processingacceleration unit 3006, an I/O subsystem 3008, a storage subsystem 3018and a communications subsystem 3024. Storage subsystem 3018 includestangible computer-readable storage media 3022 and a system memory 3010.

Bus subsystem 3002 provides a mechanism for letting the variouscomponents and subsystems of computer system 3000 communicate with eachother as intended. Although bus subsystem 3002 is shown schematically asa single bus, alternative aspects of the bus subsystem may utilizemultiple buses. Bus subsystem 3002 may be any of several types of busstructures including a memory bus or memory controller, a peripheralbus, and a local bus using any of a variety of bus architectures. Forexample, such architectures may include an Industry StandardArchitecture (ISA) bus, Micro Channel Architecture (MCA) bus, EnhancedISA (EISA) bus, Video Electronics Standards Association (VESA) localbus, and Peripheral Component Interconnect (PCI) bus, which can beimplemented as a Mezzanine bus manufactured to the IEEE P3086.1standard.

Processing unit 3004, which can be implemented as one or more integratedcircuits (e.g., a conventional microprocessor or microcontroller),controls the operation of computer system 3000. One or more processorsmay be included in processing unit 3004. These processors may includesingle core or multicore processors. In certain aspects, processing unit3004 may be implemented as one or more independent processing units 3032and/or 3034 with single or multicore processors included in eachprocessing unit. In other aspects, processing unit 3004 may also beimplemented as a quad-core processing unit formed by integrating twodual-core processors into a single chip.

In various aspects, processing unit 3004 can execute a variety ofprograms in response to program code and can maintain multipleconcurrently executing programs or processes. At any given time, some orall of the program code to be executed can be resident in processor(s)3004 and/or in storage subsystem 3018. Through suitable programming,processor(s) 3004 can provide various functionalities described above.Computer system 3000 may additionally include a processing accelerationunit 3006, which can include a digital signal processor (DSP), aspecial-purpose processor, and/or the like.

I/O subsystem 3008 may include user interface input devices and userinterface output devices. User interface input devices may include akeyboard, pointing devices such as a mouse or trackball, a touchpad ortouch screen incorporated into a display, a scroll wheel, a click wheel,a dial, a button, a switch, a keypad, audio input devices with voicecommand recognition systems, microphones, and other types of inputdevices. User interface input devices may include, for example, motionsensing and/or gesture recognition devices such as the Microsoft Kinect®motion sensor that enables users to control and interact with an inputdevice, such as the Microsoft Xbox® 360 game controller, through anatural user interface using gestures and spoken commands. Userinterface input devices may also include eye gesture recognition devicessuch as the Google Glass® blink detector that detects eye activity(e.g., ‘blinking’ while taking pictures and/or making a menu selection)from users and transforms the eye gestures as input into an input device(e.g., Google Glass®). Additionally, user interface input devices mayinclude voice recognition sensing devices that enable users to interactwith voice recognition systems (e.g., Siri® navigator), through voicecommands.

User interface input devices may also include, without limitation, threedimensional (3D) mice, joysticks or pointing sticks, gamepads andgraphic tablets, and audio/visual devices such as speakers, digitalcameras, digital camcorders, portable media players, webcams, imagescanners, fingerprint scanners, barcode reader 3D scanners, 3D printers,laser rangefinders, and eye gaze tracking devices. Additionally, userinterface input devices may include, for example, medical imaging inputdevices such as computed tomography, magnetic resonance imaging,position emission tomography, medical ultrasonography devices. Userinterface input devices may also include, for example, audio inputdevices such as MIDI keyboards, digital musical instruments and thelike.

User interface output devices may include a display subsystem, indicatorlights, or non-visual displays such as audio output devices, etc. Thedisplay subsystem may be a cathode ray tube (CRT), a flat-panel device,such as that using a liquid crystal display (LCD) or plasma display, aprojection device, a touch screen, and the like. In general, use of theterm “output device” is intended to include all possible types ofdevices and mechanisms for outputting information from computer system3000 to a user or other computer. For example, user interface outputdevices may include, without limitation, a variety of display devicesthat visually convey text, graphics and audio/video information such asmonitors, printers, speakers, headphones, automotive navigation systems,plotters, voice output devices, and modems.

Computer system 3000 may comprise a storage subsystem 3018 thatcomprises software elements, shown as being currently located within asystem memory 3010. System memory 3010 may store program instructionsthat are loadable and executable on processing unit 3004, as well asdata generated during the execution of these programs.

Depending on the configuration and type of computer system 3000, systemmemory 3010 may be volatile (such as random access memory (RAM)) and/ornon-volatile (such as read-only memory (ROM), flash memory, etc.) TheRAM typically contains data and/or program modules that are immediatelyaccessible to and/or presently being operated and executed by processingunit 3004. In some implementations, system memory 3010 may includemultiple different types of memory, such as static random access memory(SRAM) or dynamic random access memory (DRAM). In some implementations,a basic input/output system (BIOS), containing the basic routines thathelp to transfer information between elements within computer system3000, such as during start-up, may typically be stored in the ROM. Byway of example, and not limitation, system memory 3010 also illustratesapplication programs 3012, which may include client applications, Webbrowsers, mid-tier applications, relational database management systems(RDBMS), etc., program data 3014, and an operating system 3016. By wayof example, operating system 3016 may include various versions ofMicrosoft Windows®, Apple Macintosh®, and/or Linux operating systems, avariety of commercially-available UNIX® or UNIX-like operating systems(including without limitation the variety of GNU/Linux operatingsystems, the Google Chrome® OS, and the like) and/or mobile operatingsystems such as iOS, Windows® Phone, Android® OS, BlackBerry® 10 OS, andPalm® OS operating systems.

Storage subsystem 3018 may also provide a tangible computer-readablestorage medium for storing the basic programming and data constructsthat provide the functionality of some aspects. Software (programs, codemodules, instructions) that when executed by a processor provide thefunctionality described above may be stored in storage subsystem 3018.These software modules or instructions may be executed by processingunit 3004. Storage subsystem 3018 may also provide a repository forstoring data used in accordance with the present invention.

Storage subsystem 3000 may also include a computer-readable storagemedia reader 3020 that can further be connected to computer-readablestorage media 3022. Together and, optionally, in combination with systemmemory 3010, computer-readable storage media 3022 may comprehensivelyrepresent remote, local, fixed, and/or removable storage devices plusstorage media for temporarily and/or more permanently containing,storing, transmitting, and retrieving computer-readable information.

Computer-readable storage media 3022 containing code, or portions ofcode, can also include any appropriate media known or used in the art,including storage media and communication media, such as but not limitedto, volatile and non-volatile, removable and non-removable mediaimplemented in any method or technology for storage and/or transmissionof information. This can include tangible, non-transitorycomputer-readable storage media such as RAM, ROM, electronicallyerasable programmable ROM (EEPROM), flash memory or other memorytechnology, CD-ROM, digital versatile disk (DVD), or other opticalstorage, magnetic cassettes, magnetic tape, magnetic disk storage orother magnetic storage devices, or other tangible computer readablemedia. When specified, this can also include nontangible, transitorycomputer-readable media, such as data signals, data transmissions, orany other medium which can be used to transmit the desired informationand which can be accessed by computing system 3000.

By way of example, computer-readable storage media 3022 may include ahard disk drive that reads from or writes to non-removable, nonvolatilemagnetic media, a magnetic disk drive that reads from or writes to aremovable, nonvolatile magnetic disk, and an optical disk drive thatreads from or writes to a removable, nonvolatile optical disk such as aCD ROM, DVD, and Blu-Ray® disk, or other optical media.Computer-readable storage media 3022 may include, but is not limited to,Zip® drives, flash memory cards, universal serial bus (USB) flashdrives, secure digital (SD) cards, DVD disks, digital video tape, andthe like. Computer-readable storage media 3022 may also include,solid-state drives (SSD) based on non-volatile memory such asflash-memory based SSDs, enterprise flash drives, solid state ROM, andthe like, SSDs based on volatile memory such as solid state RAM, dynamicRAM, static RAM, DRAM-based SSDs, magnetoresistive RAM (MRAM) SSDs, andhybrid SSDs that use a combination of DRAM and flash memory based SSDs.The disk drives and their associated computer-readable media may providenon-volatile storage of computer-readable instructions, data structures,program modules, and other data for computer system 3000.

Communications subsystem 3024 provides an interface to other computersystems and networks. Communications subsystem 3024 serves as aninterface for receiving data from and transmitting data to other systemsfrom computer system 3000. For example, communications subsystem 3024may enable computer system 3000 to connect to one or more devices viathe Internet. In some aspects, communications subsystem 3024 can includeradio frequency (RF) transceiver components for accessing wireless voiceand/or data networks (e.g., using cellular telephone technology,advanced data network technology, such as 3G, 4G or EDGE (enhanced datarates for global evolution), WiFi (IEEE 802.28 family standards, orother mobile communication technologies, or any combination thereof),global positioning system (GPS) receiver components, and/or othercomponents. In some aspects, communications subsystem 3024 can providewired network connectivity (e.g., Ethernet) in addition to or instead ofa wireless interface.

In some aspects, communications subsystem 3024 may also receive inputcommunication in the form of structured and/or unstructured data feeds3026, event streams 3028, event updates 3030, and the like on behalf ofone or more users who may use computer system 3000.

By way of example, communications subsystem 3024 may be configured toreceive unstructured data feeds 3026 in real-time from users of socialmedia networks and/or other communication services such as Twitter®feeds, Facebook® updates, web feeds such as Rich Site Summary (RSS)feeds, and/or real-time updates from one or more third party informationsources.

Additionally, communications subsystem 3024 may also be configured toreceive data in the form of continuous data streams, which may includeevent streams 3028 of real-time events and/or event updates 3030, thatmay be continuous or unbounded in nature with no explicit end. Examplesof applications that generate continuous data may include, for example,sensor data applications, financial tickers, network performancemeasuring tools (e.g. network monitoring and traffic managementapplications), clickstream analysis tools, automobile trafficmonitoring, and the like.

Communications subsystem 3024 may also be configured to output thestructured and/or unstructured data feeds 3026, event streams 3028,event updates 3030, and the like to one or more databases that may be incommunication with one or more streaming data source computers coupledto computer system 3000.

Computer system 3000 can be one of various types, including a handheldportable device (e.g., an iPhone® cellular phone, an iPad® computingtablet, a PDA), a wearable device (e.g., a Google Glass® head mounteddisplay), a PC, a workstation, a mainframe, a kiosk, a server rack, orany other data processing system.

Due to the ever-changing nature of computers and networks, thedescription of computer system 3000 depicted in the figure is intendedonly as a specific example. Many other configurations having more orfewer components than the system depicted in the figure are possible.For example, customized hardware might also be used and/or particularelements might be implemented in hardware, firmware, software (includingapplets), or a combination. Further, connection to other computingdevices, such as network input/output devices, may be employed. Based onthe disclosure and teachings provided herein, a person of ordinary skillin the art will appreciate other ways and/or methods to implement thevarious aspects.

In the foregoing specification, aspects of the invention are describedwith reference to specific aspects thereof, but those skilled in the artwill recognize that the invention is not limited thereto. Variousfeatures and aspects of the above-described invention may be usedindividually or jointly. Further, aspects can be utilized in any numberof environments and applications beyond those described herein withoutdeparting from the broader spirit and scope of the specification. Thespecification and drawings are, accordingly, to be regarded asillustrative rather than restrictive.

What is claimed is:
 1. A computer-implemented method comprising:accessing a sentence comprising a plurality of fragments, wherein atleast one fragment comprises a verb and a plurality of words, each wordcomprising a role of the words within the fragment, wherein eachfragment is an elementary discourse unit; generating a discourse treethat represents rhetorical relationships between the plurality offragments, wherein the discourse tree comprises a plurality of nodes,each nonterminal node representing a rhetorical relationship between twoof the plurality of fragments, each terminal node of the nodes of thediscourse tree is associated with one of the plurality of fragments;matching each fragment that has a verb to a verb signature, therebycreating a communicative discourse tree, the matching comprising:accessing a plurality of verb signatures, wherein each verb signaturecomprises the verb of a fragment and a sequence of thematic roles,wherein each thematic role describes a respective relationship betweenthe verb and related words; determining, for each verb signature of theplurality of verb signatures, a plurality of thematic roles of therespective verb signature, wherein each of the thematic roles matches arole of a word in the fragment; selecting a particular verb signaturefrom the plurality of verb signatures based on the particular verbsignature comprising a highest number of matches of roles; andassociating the particular verb signature with the fragment; identifyinga correspondence between the communicative discourse tree and anadditional communicative discourse tree from a plurality ofcommunicative discourse trees; and sending text associated with theadditional communicative discourse tree to an external device.
 2. Themethod of claim 1, wherein the sentence is a question received from theexternal device, the method further comprising: accessing a plurality ofcandidate answers; and determining the plurality of communicativediscourse trees by creating, for each candidate answer of the pluralityof candidate answers, a respective communicative discourse tree.
 3. Themethod of claim 1, wherein the associating further comprises:identifying each of the plurality of thematic roles in the particularverb signature; and matching, for each of the plurality of thematicroles in the particular verb signature, a corresponding word in thefragment to the thematic role.
 4. The method of claim 1, furthercomprising: identifying, from the plurality of fragments, a firstfragment and a second fragment, the first fragment having a first verbsignature and the second fragment having a second verb signature,wherein the first verb signature comprises a thematic role; determiningthat the second fragment corresponds to the thematic role of the firstfragment; and associating a nonterminal node with an updated first verbsignature comprising the first verb signature and the second verbsignature.
 5. The method of claim 1, wherein the verb is a communicativeverb.
 6. The method of claim 1, wherein each verb signature of theplurality of verb signatures comprises one of (i) an adverb, (ii) a nounphrase, or (iii) a noun.
 7. The method of claim 1, wherein theidentifying comprises: merging the additional communicative discoursetree with the communicative discourse tree; and computing a level ofcomplementarity between the additional communicative discourse tree andthe communicative discourse tree by applying a predictive model to themerged communicative discourse tree.
 8. The method of claim 7, whereinthe predictive model is a machine learning algorithm that is trained todetermine a level of complementarity between two communicative discoursetrees identified as matching or not matching.
 9. A non-transitorycomputer-readable storage medium storing computer-executable programinstructions, wherein when executed by a processing device, the programinstructions cause the processing device to perform operationscomprising: accessing a sentence comprising a plurality of fragments,wherein at least one fragment comprises a verb and a plurality of words,each word comprising a role of the words within the fragment, whereineach fragment is an elementary discourse unit; generating a discoursetree that represents rhetorical relationships between the plurality offragments, wherein the discourse tree comprises a plurality of nodes,each nonterminal node representing a rhetorical relationship between twoof the plurality of fragments, each terminal node of the nodes of thediscourse tree is associated with one of the plurality of fragments;matching each fragment that has a verb to a verb signature, therebycreating a communicative discourse tree, the matching comprising:accessing a plurality of verb signatures, wherein each verb signaturecomprises the verb of a fragment and a sequence of thematic roles,wherein each thematic role describes a respective relationship betweenthe verb and related words; determining, for each verb signature of theplurality of verb signatures, a plurality of thematic roles of therespective verb signature, wherein each of the thematic roles matches arole of a word in the fragment; selecting a particular verb signaturefrom the plurality of verb signatures based on the particular verbsignature comprising a highest number of matches of roles; andassociating the particular verb signature with the fragment; identifyinga complementarity between the communicative discourse tree and anadditional communicative discourse tree from a plurality ofcommunicative discourse trees; and sending text associated with theadditional communicative discourse tree to an external device.
 10. Thenon-transitory computer-readable storage medium of claim 9, theoperations further comprising: receiving, from the external device, arequest comprising a question; accessing a plurality of candidateanswers; determining a plurality of candidate answer communicativediscourse trees by creating, for each candidate answer of the pluralityof candidate answers, a communicative discourse tree; determining, foreach of the candidate answers, a score based on a comparison between arespective candidate answer communicative discourse tree and thecommunicative discourse tree; and providing, to the external device, ananswer corresponding to the communicative discourse tree with a highestscore.
 11. The non-transitory computer-readable storage medium of claim9, wherein the associating further comprises: identifying each of theplurality of thematic roles in the particular verb signature; andmatching, for each of the plurality of thematic roles in the particularverb signature, a corresponding word in the fragment to the thematicrole.
 12. The non-transitory computer-readable storage medium of claim9, the operations further comprising: identifying, from the plurality offragments, a first fragment and a second fragment, the first fragmenthaving a first signature and the second fragment having a secondsignature, wherein the first signature comprises a thematic role;determining that the second fragment corresponds to the thematic role ofthe first fragment; and associating a nonterminal node with an updatedfirst signature comprising the first signature and the second signature.13. The non-transitory computer-readable storage medium of claim 9,wherein the verb is a communicative verb.
 14. The non-transitorycomputer-readable storage medium of claim 9, wherein each verb signatureof the plurality of verb signatures comprises one of (i) an adverb, (ii)a noun phrase, or (iii) a noun.
 15. The non-transitory computer-readablestorage medium of claim 9, wherein the identifying comprises: mergingthe additional communicative discourse tree with the communicativediscourse tree; and computing a level of complementarity betweenadditional communicative discourse tree and the communicative discoursetree by applying a predictive model to the merged communicativediscourse tree.
 16. A system comprising: a non-transitorycomputer-readable medium storing computer-executable programinstructions; and a processing device communicatively coupled to thenon-transitory computer-readable medium for executing thecomputer-executable program instructions, wherein executing thecomputer-executable program instructions configures the processingdevice to perform operations comprising: accessing a sentence comprisinga plurality of fragments, wherein at least one fragment comprises a verband a plurality of words, each word comprising a role of the wordswithin the fragment, wherein each fragment is an elementary discourseunit, and wherein the sentence corresponds to a question; generating adiscourse tree that represents rhetorical relationships between theplurality of fragments, wherein the discourse tree comprises a pluralityof nodes, each nonterminal node representing a rhetorical relationshipbetween two of the plurality of fragments, each terminal node of thenodes of the discourse tree is associated with one of the plurality offragments; matching each fragment that has a verb to a verb signature,thereby creating a communicative discourse tree, the matchingcomprising: accessing a plurality of verb signatures, wherein each verbsignature comprises the verb of a fragment and a sequence of thematicroles, wherein a thematic role describes a relationship between the verband related words; determining, for each verb signature of the pluralityof verb signatures, a plurality of thematic roles of the respectivesignature, wherein each of the thematic roles matches a role of a wordin the fragment; selecting a particular verb signature from theplurality of verb signatures based on the particular verb signaturecomprising a highest number of matches; and associating the particularverb signature with the fragment; determining a plurality of candidateanswer communicative discourse trees by creating, for each candidateanswer of a plurality of candidate answers, a candidate answercommunicative discourse tree; determining, for each of the candidateanswers, a score based on a comparison between a respective candidateanswer communicative discourse tree and the communicative discoursetree; and providing, to a device, an answer corresponding to thecandidate answer communicative discourse tree with a highest score. 17.The system of claim 16, wherein the associating further comprises:identifying each of the plurality of thematic roles in the particularverb signature; and matching, for each of the plurality of thematicroles in the particular verb signature, a corresponding word in thefragment to the thematic role.
 18. The system of claim 16, furthercomprising: identifying, from the plurality of fragments, a firstfragment and a second fragment, the first fragment having a first verbsignature and the second fragment having a second verb signature, andwherein the first verb signature comprises a thematic role; determiningthat the second fragment corresponds to the thematic role of the firstfragment; and associating a nonterminal node with an updated first verbsignature comprising the first verb signature and the second verbsignature.
 19. The system of claim 16, wherein the verb is acommunicative verb.
 20. The system of claim 16, wherein determining thescore comprises computing a level of complementarity between therespective candidate answer communicative discourse tree and thecommunicative discourse tree by applying a predictive model to themerged communicative discourse tree.